MAY – to be allowed (permitted) to do smth.

	meaning	use	present	past
1.	permission	+ /?	You may use my ISP if you wish.	-
2.	prohibition	-	You may not use my e-mail box.	-
3.	possibility	+ / -	It may/might be a faulty program.	The modem may/might not have been switched on.
4.	suggestion	+	We might use other graphical software.	-
5.	complaint	+	They might pay more attention to the instructions.	He might have checked his e-mail at least sometimes.

Notes:

1. May has only two tense forms: may (present) and might (past), so for other tenses to be allowed (permitted) to do sth. is used.

2. Might is not always the past of may, sometimes it has a present or future meaning. Perfect infinitive after may or might in such cases shows that they refer to the past.

3. Passive and progressive infinitives after may or might are also possible in some cases.

 

Упражнение 2. Прочтите и переведите следующие предложения, обращая внимание на значение модального глагола may либо его эквиваленты и форму инфинитива после них:

1. This device may not be switched on here. 2. At first the desktop might seem a little foreign to you. 3. It’s also more installation procedures than you might expect. 4. Will she be allowed to process these figures? 5. It may have beensaid that the development of modern computers was entirely depended upon developments in integrated circuits. 6. Different combinations of 1s and 0s may be used to represent numbers and characters (letters of the alphabet special characters). 7. Were they allowed to operate that new device? 8. Programs other than the one that is being obeyed may be stored on a backing-store external to the computer memory. 9. You may not be the only person using the program and this is the factor to be considered. 10. Combining both of these technologies might produce a completely new range of possibilities for user of information technology.

 

MUST

	meaning	use	present	past
1.	obligation (speaker’s authority)	+?	They must provide us with all necessary data.	-
2.	necessity (speaker’s thought)	+	He must work hard to learn this computer language.	-
3.	prohibition	-	You mustn’t press any button.	-
4.	certainty	+	He must be working in the Internet. I can’t call him.	They must have already opened this file.

Notes:

1. Must has no other forms. To express past perfect infinitive can be used sometimes.

2. Had to is the past form of must which refers to a past obligation.

3. Need is used in its negative form to express the lack of necessity.

 

Упражнение 3. Прочтите и переведите следующие предложения, обращая внимание на значение модального глагола must либо его эквиваленты и форму инфинитива после них:

1. The data must have been lost. I don’t see it anywhere. 2. To use a CD-ROM, you must have a computer equipped with a CD-ROM drive. 3. You mustn’t interfere with the program work. 4. To read this graphics file you must have used a program that recognized the file’s format. 5. The user must create sample input data that represents every possible way to enter input.

 

SHOULD / OUGHT TO

	meaning	use	present	past
1.	advice (giving/asking for)	+ /? / -	Should these commands be carried out?	-
2.	obligation	+ / -	The files ought to be fully defined.	The PC shouldn’t have been used inappropriately.
3.	possibility	+	You should see the message on the screen.	They should have carried out the calculations.
4.	complaint	+ / -	You should be using another application for this purpose.	These devices should have been handled with great care.

Note:

Should/Ought to have no other forms. To express past perfect infinitive can be used sometimes.

 

Упражнение 4. Прочтите и переведите следующие предложения, обращая внимание на значение модальных глаголов should/ought to и форму инфинитива после них:

1. It determines which operations should be carried out and in what order. 2. They ought to have tested new applications. 3. Make sure your last command is finished. You should see the prompt on the screen. 4. The batteries should not be kept uncharged. 5. What kind of data ought to be typed?

 

NEED

	meaning	use	present	past
1.	necessity	+	To do this, you need to understand how the data bus width affects performance.	He needed to back up that file regulary.
2.	no obligation	-	You don’t need to use virus scanning every time.	You didn’t need to back up these files.

Notes:

1. Need can be used in different forms with and without “to” after it.

2. Needn’t and don’t need to are different.

- We generally use needn’t when the authority comes from the speaker and don’t need to when the authority doesn’t come from the speaker.

- To talk about the past, we use needn’t and Perfect Infinitive (means: you did but it wasn’t necessary) or didn’t need to.

 

Упражнение 5. Прочтите и переведите следующие предложения, обращая внимание на значение модального глагола need и форму инфинитива после него:

1. Most memory chips are now mounted on boards, you needn’t have checked for other ports. 2. Nonvolatile media are needed to store programs and data when the power is off. 3. The smaller size reduced the distance electrical signals needed to travel. 4. The fields need not be contiguous in memory, nor do they need to be part of a structure. 5. You can insert the executable code you need to “clean up” at an embed point.