The anatomy of a virus

1. A biological virus is a very small, simple organism that infects living cells, known as the host, by attaching itself to them and using them to reproduce itself. This often causes harm to the host cells.

2. Similarly, a computer virus is a very small program routine that infects a computer system and uses its resources to reproduce itself. It often does this by patching the operating system to enable it to detect program files, such as COM or EXE files. It then copies itself into those files. This sometimes causes harm to the host computer system.

3. When the user runs an infected program, it is loaded into memory carrying the virus. The virus uses a common programming technique to stay resident in memory. It can then use a reproduction routine to infect other programs. This process continues until the computer is switched off.

4. The virus may also contain a payload that remains dormant until a trigger event activates it, such as the user pressing a particular key. The payload can have a variety of forms. It might do something relatively harmless such as displaying a message on the monitor screen or it might do something more destructive such as deleting files on the hard disk.

5. When it infects a file, the virus replaces the first instruction in the host program with a command that changes the normal execution sequence. This type of command is known as a JUMP command and causes the virus instructions to be executed before the host program. The virus then returns control to the host program which then continues with its normal sequence of instructions and is executed in the normal way.

6. To be a virus, a program only needs to have a reproduction routine that enables it to infect other programs. Viruses can, however, have four main parts. A misdirection routine that enables it to hide itself; a reproduction routine that allows it to copy itself to other programs; a trigger that causes the payload to be activated at a particular time or when a particular event takes place; and a payload that may be a fairly harmless joke or may be very destructive. A program that has a payload but does not have a reproduction routine is known as a Trojan.

Questions:

1. What is a computer virus? 2. In what way does a virus infect a computer system? 3. What does a virus use to stay resident in memory? 4. What sort of routine does a program need to have to be a virus? 5. What program is known as a Trojan?

II. Перепишите и письменно переведите 4 и 6 абзацы текста.

III. Определите тип условных предложений и письменно переведите их, обращая внимание на разницу в переводе форм сослагательного наклонения во II, III типах условных предложений и форм изъявительного наклонения в предложениях I типа.

1. Without special devices the solution of such complicated problems would be impossible. 2. If the model fits well, the observed data will be correct. 3. A valuable contribution would be made if considerable efforts were devoted to the theoretic examination. 4. If you had made use of logarithms, you could have found them very helpful. 5. If you studied hard, you would have managed to achieve your task. 6. Had he been aware of this fact, he would have been more cautious. 7. But for the teacher’s help, the students would have failed their experiment.

IV. Определите тип условных предложений. Выберите правильный вариант формы глагола. Письменно переведите предложения.

1. If the distance between the Sun and the Earth (had been/were/is) less, the temperature on the surface of the Earth would be much higher. 2. We (could/will be able/can) go on with our work if our assumptions were correct. 3. Unless computer techniques (have been developed/had been developed/were developed), space research would have never made such great progress. 4. If the teacher (had introduced/has introduced/introduced) the law of exponents at the previous lecture, you could make use of it for evaluating the result now. 5. (Had/Has/Should) I been given the article, I could have translated it by now. 6. If it (hadn’t been/were not/had been) for her help, we wouldn’t have obtained the information required.

V. Выберите правильный вариант формы глагола в сослагательном наклонении в конструкциях, содержащих wish/if only. Письменно переведите предложения.

1. I wish I (could/can/shall) establish a one-to-one correspondence between the elements of the two sets. 2. They wish education (will be/were/has been) enhanced using all or most of the human senses. 3. He wishes he (had distinguished/should distinguish/will distinguish) a family of elements X from the subset of X. 4. All computer users wish hackers (don’t steal/would not steal/won’t steal) their passwords and private information. 5. If only he (has clarified/had clarified/should clarify) that notation! 6. If only I (knew/have known/will know) how to solve the first problem!

VI. Переведите письменно предложения, учитывая способы перевода придаточных предложений и оборотов, содержащих формы сослагательного наклонения.

1. I’d rather get a closer approximation by adding digits at the right. 2. You‘d better emphasize that positive integers form a set regardless of order. 3. It’s high time I went home. 4. It’s desirable that we should consider a special case of many-one correspondence. 5. He suggested that an infinite set should be studied as a whole. 6. Most mathematicians continued to develop their theories as if the crisis in the foundations of maths had not concerned them. 7. He feared lest all his efforts should be useless.

VII. Выберите правильный вариант и письменно переведите предложения, содержащие формы сослагательного наклонения.

1. I (would better/would rather/had rather) clear up the situation. 2. You (had better/would better/would rather) count all positive integers in their order of increasing magnitude. 3. It’s time I (finished/finish/will finish) the thesis. 4. It’s necessary that the programmer (would know/should know/knew) one or more of the standard languages and the art of programming. 5. He insisted that the students (should explain/would explain/explained) the binary system giving a specific example.

VIII. Переведите письменно предложения, обращая внимание на то, как переводятся модальные глаголы в сочетании с разными формами инфинитива.

1. They must have misunderstood the theoretical character of the issue. 2. This book must have been written years ago. 3. They may have defined the product of n sets by induction. 4. The function may have been defined as tending to infinity. 5. You might have come to a certain conclusion. 6. He should have paid more attention to constructions.