Computer Virus
Virus Introduction
Exercises
Multiple choices.
A virus is a ( A ).
A,program B,computer C,bad man D,beast
A virus is a program that reproduces its own code by ( ABC ).
A,adding to the end of a file B,inserting into the middle of a file
C,simply placing a pointer D,replacing another program
( AD )is a type of executable file,
A,COM file B,TXT file C,JPG file D,EXE file
Similar to viruses,you can also find malicious code in ( ABC ).
A,Trojan Horses B,worms
C,logic bombs D,Microsoft Word Documents
Fill in the blanks.
A virus is a program that reproduces its own code by attaching itself to other executable files in such a way that the virus code is executed when the infected executable file is executed,
To attach might mean physically adding to the end of a file,inserting into the middle of a file,or simply placing a pointer to a different location on the disk somewhere where the virus can find it.
Similar to viruses,you can also find malicious code in Trojan Horses,worms,and logic bombs.
Translate and analyze the following sentences.
These self-replicating codes,when caused by some event,may do a potentially harmful act to your computer.
句子组成,when引导时间状语从句做插入语，当…的时候,
翻译：当这些自复制代码被一些事件触发时，或许会做出一些对你的计算机有潜在危害的行为.
More recently,scripts written for Internet web sites and/or included in E-mail can also be executed and infected.
句子组成：scripts written…省略的定语从句 完整形式scripts which were writtened….
翻译：现在，为网站编写的或者包括在E-mail中的脚本也能够被执行和感染。
Reading comprehension.
Viruses can infect any type of executable code,not just the files that are commonly called,program files”,Viruses can be spread by:
Executable code in the boot sector of infected floppy disks
Executable code in the system area of infected hard drives
Word processing and spreadsheet documents that use infected macros Infected HTML documents that contain JavaScript or other types of executable code
Since virus code must be executed (run) to have any effect,files that the computer treats as pure data are safe,This includes graphics and sound files such as,gif,.jpg,.mp3,.wav,etc.,as well as plain text in,txt files,For example,just viewing picture files won't infect your computer with a virus,The virus code has to be in a form,such as an,exe program file or a Word,doc file,that the computer will actually try to execute.
Answer the following questions according to the article above.
What kind of files can be infected by a virus?
A virus can infect the executable files such as,exe or,com or,doc files,etc.
How about viruses can be spread?
Executable code in the boot sector of infected floppy disks or in the system area of infected hard drives,word processing and spreadsheet documents that use infected macros Infected HTML documents that contain JavaScript or other types of executable code.
Virus Behavior – Infection Phase
Exercises
Multiple choices.
Viruses all have two phases to their execution,the ( A ) and the ( C ).
A,infection phase B,delete phase
C,attack phase D,create phase
( ABCD ) maybe a certain cause that some viruses infect upon.
A,a day B,a time
C,an external event on your PC D,a counter within the virus
Many viruses go resident in the memory like a ( C ).
A.,exe file B.,com file
C,tsr program D,data file
You want to ( ABC ) maybe wake up a virus that has residented in memory.
A,copy a file B,access a diskette
C,execute a program D,delete a file
Some viruses use ( A ) and ( B ) techniques to hide their existence.
A,stealth B,polymorphic
C,quickly spread D,replace a part of system software
Fill in the blanks.
Viruses come in a great many different forms,but they all potentially have two phases to their execution,the infection phase and the attact phase.
For those not old enough to remember tsr,they were programs that executed under system but stayed in memory instead of ending.
Note that worms often take the opposite approach and spread as fast as possible.
Translate and analyze the following sentences.
When the virus executes it has the potential to infect other programs.
句子组成：when引导时间状语从句 当,,,时,
翻译：病毒在执行时，能够感染其他程序,
Some viruses infect other programs each time they are executed; other viruses infect only upon a certain cause.
句子组成：some…other…引导两个并列句子，一些…其他….。
翻译：一些病毒会在每次被执行时，都感染其他程序；另一些病毒只是在一些特定的触发原因下才能感染其他程序.
Resident viruses frequently take over portions of the system software on the PC to hide their existence.
句子组成：to hide their existence不定式做目的状语 take over 代替.
翻译：驻留内存病毒常常代替PC系统文件的一部分来掩饰它的存在,
Reading comprehension.
Polymorphic viruses use encryption (密码术) or other methods to change how they look,This strategy of changing their appearance helps to defeat antivirus scanning software,Stealth viruses attempt to hide any modifications they have made from antivirus scanning software,For example,stealth viruses sometimes substitute unaltered files and directory table entries for the virus-altered ones,in an attempt to fool antivirus scanning software,Fast infector viruses are capable of infecting any file which is opened,rather than only executed files,Slow infectors only modify files as the files are being created or altered for legitimate reasons,a practice which fools some antivirus software,Sparse infectors only infect at certain intervals dictated by their programming,lessening their chance of creating suspicion on the part of the user.
Choose the best answer.
How can polymorphic viruses defeat antivirus scanning software?(B)
A,resident in memory
B,use encryption
C,hide in other programs
D,use the unaltered files to replace the virus-altered ones
How can stealth viruses fool antivirus scanning software?(C)
A,resident in memory
B,use encryption
C,hide in other programs
D,use the unaltered files to replace the virus-altered ones
Which kind of virus can only alter files,as the files are being created or altered for legitimate reasons?(D)
A,polymorphic virus B,stealth virus C,fast virus D,slow virus
A few of viruses only infect at certain intervals dictated by their programming,because of ___?(A)
A,Don’t let user notice them.
B,They wait for some special programs to infect.
C,No special reason.
D,They want to change how they look.
Virus Behavior－Attack Phase Exercises
Multiple choices.
Many viruses do harmful things such as ( ABCD ).
A,deleting files B,changing random data on your disk
C,simulating typos D,slowing your PC down
Viruses can delay their attack for ( ABCD ).
A,days B,weeks
C,months D,years
If a virus simply reproduce and have no cause for an attack phase,but it will still ( AB ) without your permission.
A,stealing storage B,pilfer CPU cycles
C,delete files C,play music
Some viruses,with no attack phase,often damage the programs or disks they infect because they ( AB ).
A,have bugs in them B,contain poor quality code
C,steal storage D,show messages on your screen
Fill in the blanks.
Many viruses do unpleasant things such as deleting files or changing random data on your disk.
Most viruses have bugs in them and these bugs often cause unintended negative side effects.
In addition,even if the virus is perfect,it still steals system resources.
The attack phase is optional,many viruses simply reproduce and have no cause for an attack phase.
An example,one of the most common past viruses,Stoned,is not intentionally harmful.
Translate and analyze the following sentences.
Just as the infection phase can be caused by some event,the attack phase also has its own cause.
句子组成：as引导状语从句.
翻译：如同感染阶段需要一些事件触发一样，攻击阶段也有它自己的触发条件.
In addition,even if the virus is perfect,it still steals system resources.
句子组成：even if 即使，引导条件状语从句；in addition 另外.
翻译：此外，即使病毒设计完美，它仍会盗用系统资源。
This is made worse since viruses that "just infect," with no attack phase,often damage the programs or disks they infect.
句子组成：since引导原因状语从句 with no attact phase 插入语.
翻译：有些病毒只会“感染”而没有攻击阶段，但它们会破坏被它们感染的程序或磁盘，这反而更有害.
The original virus tried to hide its own code in an area of 1.2MB diskettes that resulted in corruption of the entire diskette (this bug was fixed in later versions of the virus).
句子组成：that引导主语从句表示the original…in an area of 1.2MB diskettes.
翻译：最初的病毒试图把它自身隐藏在1.2MB的磁盘中从而导致整张磁盘变坏.
Reading comprehension.
When you start a program that's infected by a virus,the virus code will execute (run) and try and infect other programs,This can infect the same computer or other computers connected to it on a network,The newly infected programs will try to infect more programs and computers,When you share a copy of an infected file with other computer users,opening the file may also infect their computers; and files from those computers may spread the infection to yet more computers,If your computer is infected with a boot sector virus,the virus tries to write copies of itself to the system areas of floppy disks and hard disks,Then the infected floppy disks may infect other computers that boot from them,and then the virus on the computer will try to infect more floppies inserted into it.
Answer the following two questions according to the article above.
Did you meet any viruses before?
If you have met a virus,do you remember how the virus infected your computer?
Number of Viruses Exercises
Multiple choices.
In 2000,the number of viruses topped ( D ).
A,500 B,1000
C,7500 D,50000
What make it is difficult to agree on how to count viruses?(ABCD)
A,new virus arise from an existing virus
B,some viruses can create different versions when they infect other programs
C,some viruses can use polymorphic technique
D,just a trivial change may create a new virus
The Whale will create ( D ) different versions of itself when it infects files.
A,30 B,31
C,32 D,33
Now,about ( C ) different viruses account for all the viruses that actually spread in the wild.
A,30 B,150
C,180 D,50000
Fill in the blanks.
(1) In late 1992,estimates were ranging from 1,000 to 2,300 viruses.
(2) But,this is a trivial change that can be done in less than two minutes resulting in yet another "new" virus.
(3) Another problem comes from viruses that try to conceal themselves from scanners by mutating.
Translate and analyze the following sentences.
The confusion exists partly because it's difficult to agree on how to count viruses.
句子结构：it’s difficult…中it为形式主语代替后面真正的主语to agree on ….
翻译：由于在怎样计算病毒上很难达成一致，所以现在还存在一些混乱.
But,this is a trivial change that can be done in less than two minutes resulting in yet another "new" virus.
句子结构：that引导定语从句修饰change.
翻译：但是，一个在两分钟内可以完成的细微的改动就产生了一种“新”病毒.
Many of the large number of viruses known to exist have not been detected in the wild but probably exist only in someone's virus collection.
句子结构：not…but… 不是…而是…..
翻译：很多病毒虽然还没有被公众检测到，但可能已经在某个人的病毒收集夹中了.
Although the actual number of viruses will probably continue to be hotly debated,what is clear is that the total number of viruses is increasing,although the active viruses not quite as rapidly as the numbers might suggest.
句子结构：although表转折，连接词，引导句子.
翻译：虽然关于病毒的实际数量可能会继续进行激烈的争论，但一个很清楚的事实就是病毒的总数在增加。
Reading comprehension.
Viruses are software programs; the actual effect of a virus depends on how it was programmed by the person who wrote the virus.
Some viruses are designed to overwrite boot sectors and interfere with your computer's operation (boot viruses),others damage your computers memory operation then try and spread themselves around by picking up e-mail or network addresses off your computer (worm viruses),Still others will wipe files from the hard drive and destroy system files (Trojan viruses) and finally there are ones that infect document files,electronic spreadsheets and databases of several popular software packages (Macro viruses),
Viruses can't do any damage to hardware,they won't melt down your CPU,burn out your hard drive,cause your monitor to explode,etc,Warnings about viruses that will physically destroy your computer are usually hoaxes,not legitimate virus warnings.
Make some choices after reading the article above.
The actual effect of a virus depends on ( A ).
A,the person who wrote the virus
B,how much your computer is
C,how to use your computer
D,a special cause
What kind of virus may overwrite boot sectors and interfere with your computer's operation (boot viruses),others damage?( A )
A,boot virus
B,worm virus
C,Trojan virus
D,Macro virus
A macro virus can not infect ( C ).
A,document files
B,electronic spreadsheets
C,overwrite boot sectors
D,databases of several popular software packages
How Serious are Viruses? Exercises
Fill in the blanks.
While serious if you have one,viruses are only one way your data can be damaged.
It's still clear that there are many dangerous occurrences of data corruption from causes other than from viruses.
One just has to take protective steps with anti-virus software and use some common sense when dealing with unknown files.
Because viruses and worms are deliberately written to invade and possibly damage your PC,they are the most difficult threat to guard against.
Translate and analyze the following sentences.
While serious if you have one,viruses are only one way your data can be damaged.
句子结构：while引导原因状语从句，表转折关系.
翻译：虽然如果你的机器被病毒感染会许多威协带来很严重的后果，但那只是你的数据被破坏的其中一种方式.
It just means that it's foolish to spend much money and time on addressing the threat of viruses if you've done nothing about the other more likely threats to your files.
句子结构：if引导条件状语从句，表假设；it is means that引导同位语从句。
翻译：只是说，如果没有防范其他会对你文件造成的威胁，而花费过多的时间和金钱来忙于防范病毒的威胁是不明智的.
One just has to take protective steps with anti-virus software and use some common sense when dealing with unknown files.
句子结构：；when引导时间状语从句；deal with 处理；has to 不得不.
解释：只能使用杀毒软件采取一些保护措施，或对一些未知类型文件采用一些常规的处理方法.
提高训练——语法知识不定式练习
( A ) education is the principal way of gaining status in a culture that generally stresses achievement,skillfulness,and upward mobility.
A. To acquire B, Acquire
C, Acquires D, Have acquired
We are planning ( C ) for the entrance examination for postgraduate.
A, registering B, register
C, to register D, registered
The most urgent problem now we are facing is ( B ) to learn the needed materials for the matriculation of postgraduate.
A. make our every effort B. to make our every effort
C. to our every effort D. made our efforts
—Where should I send my application?
—The Personnel Office is the place ( C ) it to.
A. sends B. be sent
C. to be sent D. to send
( A ) from others,one should take his promise.
A. To get confidence B. To getting confidence
C. To get confidences D. Getting to the confidence
提高训练——写作知识怎样表达自己的感谢范文
The author would like to thank Johnson for helping with the architecture design and Per Danvind with helping with implementing the audio proxy,This work is supported by the Centre for Distance-spanning Technology (CDT) and the Swedish Research Institute for Information Technology.
练习写一篇文章，感谢某位同学在你装配电脑的时候给予的帮助，字数在80～100之间。
Virus Introduction
Exercises
Multiple choices.
A virus is a ( A ).
A,program B,computer C,bad man D,beast
A virus is a program that reproduces its own code by ( ABC ).
A,adding to the end of a file B,inserting into the middle of a file
C,simply placing a pointer D,replacing another program
( AD )is a type of executable file,
A,COM file B,TXT file C,JPG file D,EXE file
Similar to viruses,you can also find malicious code in ( ABC ).
A,Trojan Horses B,worms
C,logic bombs D,Microsoft Word Documents
Fill in the blanks.
A virus is a program that reproduces its own code by attaching itself to other executable files in such a way that the virus code is executed when the infected executable file is executed,
To attach might mean physically adding to the end of a file,inserting into the middle of a file,or simply placing a pointer to a different location on the disk somewhere where the virus can find it.
Similar to viruses,you can also find malicious code in Trojan Horses,worms,and logic bombs.
Translate and analyze the following sentences.
These self-replicating codes,when caused by some event,may do a potentially harmful act to your computer.
句子组成,when引导时间状语从句做插入语，当…的时候,
翻译：当这些自复制代码被一些事件触发时，或许会做出一些对你的计算机有潜在危害的行为.
More recently,scripts written for Internet web sites and/or included in E-mail can also be executed and infected.
句子组成：scripts written…省略的定语从句 完整形式scripts which were writtened….
翻译：现在，为网站编写的或者包括在E-mail中的脚本也能够被执行和感染。
Reading comprehension.
Viruses can infect any type of executable code,not just the files that are commonly called,program files”,Viruses can be spread by:
Executable code in the boot sector of infected floppy disks
Executable code in the system area of infected hard drives
Word processing and spreadsheet documents that use infected macros Infected HTML documents that contain JavaScript or other types of executable code
Since virus code must be executed (run) to have any effect,files that the computer treats as pure data are safe,This includes graphics and sound files such as,gif,.jpg,.mp3,.wav,etc.,as well as plain text in,txt files,For example,just viewing picture files won't infect your computer with a virus,The virus code has to be in a form,such as an,exe program file or a Word,doc file,that the computer will actually try to execute.
Answer the following questions according to the article above.
What kind of files can be infected by a virus?
A virus can infect the executable files such as,exe or,com or,doc files,etc.
How about viruses can be spread?
Executable code in the boot sector of infected floppy disks or in the system area of infected hard drives,word processing and spreadsheet documents that use infected macros Infected HTML documents that contain JavaScript or other types of executable code.
Virus Behavior – Infection Phase
Exercises
Multiple choices.
Viruses all have two phases to their execution,the ( A ) and the ( C ).
A,infection phase B,delete phase
C,attack phase D,create phase
( ABCD ) maybe a certain cause that some viruses infect upon.
A,a day B,a time
C,an external event on your PC D,a counter within the virus
Many viruses go resident in the memory like a ( C ).
A.,exe file B.,com file
C,tsr program D,data file
You want to ( ABC ) maybe wake up a virus that has residented in memory.
A,copy a file B,access a diskette
C,execute a program D,delete a file
Some viruses use ( A ) and ( B ) techniques to hide their existence.
A,stealth B,polymorphic
C,quickly spread D,replace a part of system software
Fill in the blanks.
Viruses come in a great many different forms,but they all potentially have two phases to their execution,the infection phase and the attact phase.
For those not old enough to remember tsr,they were programs that executed under system but stayed in memory instead of ending.
Note that worms often take the opposite approach and spread as fast as possible.
Translate and analyze the following sentences.
When the virus executes it has the potential to infect other programs.
句子组成：when引导时间状语从句 当,,,时,
翻译：病毒在执行时，能够感染其他程序,
Some viruses infect other programs each time they are executed; other viruses infect only upon a certain cause.
句子组成：some…other…引导两个并列句子，一些…其他….。
翻译：一些病毒会在每次被执行时，都感染其他程序；另一些病毒只是在一些特定的触发原因下才能感染其他程序.
Resident viruses frequently take over portions of the system software on the PC to hide their existence.
句子组成：to hide their existence不定式做目的状语 take over 代替.
翻译：驻留内存病毒常常代替PC系统文件的一部分来掩饰它的存在,
Reading comprehension.
Polymorphic viruses use encryption (密码术) or other methods to change how they look,This strategy of changing their appearance helps to defeat antivirus scanning software,Stealth viruses attempt to hide any modifications they have made from antivirus scanning software,For example,stealth viruses sometimes substitute unaltered files and directory table entries for the virus-altered ones,in an attempt to fool antivirus scanning software,Fast infector viruses are capable of infecting any file which is opened,rather than only executed files,Slow infectors only modify files as the files are being created or altered for legitimate reasons,a practice which fools some antivirus software,Sparse infectors only infect at certain intervals dictated by their programming,lessening their chance of creating suspicion on the part of the user.
Choose the best answer.
How can polymorphic viruses defeat antivirus scanning software?(B)
A,resident in memory
B,use encryption
C,hide in other programs
D,use the unaltered files to replace the virus-altered ones
How can stealth viruses fool antivirus scanning software?(C)
A,resident in memory
B,use encryption
C,hide in other programs
D,use the unaltered files to replace the virus-altered ones
Which kind of virus can only alter files,as the files are being created or altered for legitimate reasons?(D)
A,polymorphic virus B,stealth virus C,fast virus D,slow virus
A few of viruses only infect at certain intervals dictated by their programming,because of ___?(A)
A,Don’t let user notice them.
B,They wait for some special programs to infect.
C,No special reason.
D,They want to change how they look.
Virus Behavior－Attack Phase Exercises
Multiple choices.
Many viruses do harmful things such as ( ABCD ).
A,deleting files B,changing random data on your disk
C,simulating typos D,slowing your PC down
Viruses can delay their attack for ( ABCD ).
A,days B,weeks
C,months D,years
If a virus simply reproduce and have no cause for an attack phase,but it will still ( AB ) without your permission.
A,stealing storage B,pilfer CPU cycles
C,delete files C,play music
Some viruses,with no attack phase,often damage the programs or disks they infect because they ( AB ).
A,have bugs in them B,contain poor quality code
C,steal storage D,show messages on your screen
Fill in the blanks.
Many viruses do unpleasant things such as deleting files or changing random data on your disk.
Most viruses have bugs in them and these bugs often cause unintended negative side effects.
In addition,even if the virus is perfect,it still steals system resources.
The attack phase is optional,many viruses simply reproduce and have no cause for an attack phase.
An example,one of the most common past viruses,Stoned,is not intentionally harmful.
Translate and analyze the following sentences.
Just as the infection phase can be caused by some event,the attack phase also has its own cause.
句子组成：as引导状语从句.
翻译：如同感染阶段需要一些事件触发一样，攻击阶段也有它自己的触发条件.
In addition,even if the virus is perfect,it still steals system resources.
句子组成：even if 即使，引导条件状语从句；in addition 另外.
翻译：此外，即使病毒设计完美，它仍会盗用系统资源。
This is made worse since viruses that "just infect," with no attack phase,often damage the programs or disks they infect.
句子组成：since引导原因状语从句 with no attact phase 插入语.
翻译：有些病毒只会“感染”而没有攻击阶段，但它们会破坏被它们感染的程序或磁盘，这反而更有害.
The original virus tried to hide its own code in an area of 1.2MB diskettes that resulted in corruption of the entire diskette (this bug was fixed in later versions of the virus).
句子组成：that引导主语从句表示the original…in an area of 1.2MB diskettes.
翻译：最初的病毒试图把它自身隐藏在1.2MB的磁盘中从而导致整张磁盘变坏.
Reading comprehension.
When you start a program that's infected by a virus,the virus code will execute (run) and try and infect other programs,This can infect the same computer or other computers connected to it on a network,The newly infected programs will try to infect more programs and computers,When you share a copy of an infected file with other computer users,opening the file may also infect their computers; and files from those computers may spread the infection to yet more computers,If your computer is infected with a boot sector virus,the virus tries to write copies of itself to the system areas of floppy disks and hard disks,Then the infected floppy disks may infect other computers that boot from them,and then the virus on the computer will try to infect more floppies inserted into it.
Answer the following two questions according to the article above.
Did you meet any viruses before?
If you have met a virus,do you remember how the virus infected your computer?
Number of Viruses Exercises
Multiple choices.
In 2000,the number of viruses topped ( D ).
A,500 B,1000
C,7500 D,50000
What make it is difficult to agree on how to count viruses?(ABCD)
A,new virus arise from an existing virus
B,some viruses can create different versions when they infect other programs
C,some viruses can use polymorphic technique
D,just a trivial change may create a new virus
The Whale will create ( D ) different versions of itself when it infects files.
A,30 B,31
C,32 D,33
Now,about ( C ) different viruses account for all the viruses that actually spread in the wild.
A,30 B,150
C,180 D,50000
Fill in the blanks.
(1) In late 1992,estimates were ranging from 1,000 to 2,300 viruses.
(2) But,this is a trivial change that can be done in less than two minutes resulting in yet another "new" virus.
(3) Another problem comes from viruses that try to conceal themselves from scanners by mutating.
Translate and analyze the following sentences.
The confusion exists partly because it's difficult to agree on how to count viruses.
句子结构：it’s difficult…中it为形式主语代替后面真正的主语to agree on ….
翻译：由于在怎样计算病毒上很难达成一致，所以现在还存在一些混乱.
But,this is a trivial change that can be done in less than two minutes resulting in yet another "new" virus.
句子结构：that引导定语从句修饰change.
翻译：但是，一个在两分钟内可以完成的细微的改动就产生了一种“新”病毒.
Many of the large number of viruses known to exist have not been detected in the wild but probably exist only in someone's virus collection.
句子结构：not…but… 不是…而是…..
翻译：很多病毒虽然还没有被公众检测到，但可能已经在某个人的病毒收集夹中了.
Although the actual number of viruses will probably continue to be hotly debated,what is clear is that the total number of viruses is increasing,although the active viruses not quite as rapidly as the numbers might suggest.
句子结构：although表转折，连接词，引导句子.
翻译：虽然关于病毒的实际数量可能会继续进行激烈的争论，但一个很清楚的事实就是病毒的总数在增加。
Reading comprehension.
Viruses are software programs; the actual effect of a virus depends on how it was programmed by the person who wrote the virus.
Some viruses are designed to overwrite boot sectors and interfere with your computer's operation (boot viruses),others damage your computers memory operation then try and spread themselves around by picking up e-mail or network addresses off your computer (worm viruses),Still others will wipe files from the hard drive and destroy system files (Trojan viruses) and finally there are ones that infect document files,electronic spreadsheets and databases of several popular software packages (Macro viruses),
Viruses can't do any damage to hardware,they won't melt down your CPU,burn out your hard drive,cause your monitor to explode,etc,Warnings about viruses that will physically destroy your computer are usually hoaxes,not legitimate virus warnings.
Make some choices after reading the article above.
The actual effect of a virus depends on ( A ).
A,the person who wrote the virus
B,how much your computer is
C,how to use your computer
D,a special cause
What kind of virus may overwrite boot sectors and interfere with your computer's operation (boot viruses),others damage?( A )
A,boot virus
B,worm virus
C,Trojan virus
D,Macro virus
A macro virus can not infect ( C ).
A,document files
B,electronic spreadsheets
C,overwrite boot sectors
D,databases of several popular software packages
How Serious are Viruses? Exercises
Fill in the blanks.
While serious if you have one,viruses are only one way your data can be damaged.
It's still clear that there are many dangerous occurrences of data corruption from causes other than from viruses.
One just has to take protective steps with anti-virus software and use some common sense when dealing with unknown files.
Because viruses and worms are deliberately written to invade and possibly damage your PC,they are the most difficult threat to guard against.
Translate and analyze the following sentences.
While serious if you have one,viruses are only one way your data can be damaged.
句子结构：while引导原因状语从句，表转折关系.
翻译：虽然如果你的机器被病毒感染会许多威协带来很严重的后果，但那只是你的数据被破坏的其中一种方式.
It just means that it's foolish to spend much money and time on addressing the threat of viruses if you've done nothing about the other more likely threats to your files.
句子结构：if引导条件状语从句，表假设；it is means that引导同位语从句。
翻译：只是说，如果没有防范其他会对你文件造成的威胁，而花费过多的时间和金钱来忙于防范病毒的威胁是不明智的.
One just has to take protective steps with anti-virus software and use some common sense when dealing with unknown files.
句子结构：；when引导时间状语从句；deal with 处理；has to 不得不.
解释：只能使用杀毒软件采取一些保护措施，或对一些未知类型文件采用一些常规的处理方法.
提高训练——语法知识不定式练习
( A ) education is the principal way of gaining status in a culture that generally stresses achievement,skillfulness,and upward mobility.
A. To acquire B, Acquire
C, Acquires D, Have acquired
We are planning ( C ) for the entrance examination for postgraduate.
A, registering B, register
C, to register D, registered
The most urgent problem now we are facing is ( B ) to learn the needed materials for the matriculation of postgraduate.
A. make our every effort B. to make our every effort
C. to our every effort D. made our efforts
—Where should I send my application?
—The Personnel Office is the place ( C ) it to.
A. sends B. be sent
C. to be sent D. to send
( A ) from others,one should take his promise.
A. To get confidence B. To getting confidence
C. To get confidences D. Getting to the confidence
提高训练——写作知识怎样表达自己的感谢范文
The author would like to thank Johnson for helping with the architecture design and Per Danvind with helping with implementing the audio proxy,This work is supported by the Centre for Distance-spanning Technology (CDT) and the Swedish Research Institute for Information Technology.
练习写一篇文章，感谢某位同学在你装配电脑的时候给予的帮助，字数在80～100之间。
