HAVE TO

	meaning	use	example
1.	necessity (circumstantial)	+ / -	You have to follow a number of rules when entering these commands.

Notes:

1. Have to can be used in all forms (present, past, future).

2. The difference between must and have to is that with must the speaker is giving his own feelings, while with have to he is just giving facts.

3. Mustn’t and don’t have to are completely different. “You mustn’t do something” means “it’s necessary that you do not do it”. When “you don’t have to do something” means “it is not necessary to do it; you don’t need to do it”.

Упражнение 6. Прочтите и переведите следующие предложения, обращая внимание на значение модального глагола have to и форму инфинитива после него:

1. You don’t have to push buttons; these actions occur under the direction of the program you are using. 2. If the program is designed to be sold commercially, the documentation will have to include directions for the user to install the program and begin working with it. 3. You have to remember which entity (set of fields) you described as “left” and which ones as “right”. 4. You won’t have to compete with other users to gain access to the system. 5. Because of its cost, new information had to be stored in appropriate archives and libraries for use by others.

BE TO

	meaning	use	example
1.	planned action or agreement	+ /?	Old PCs are to be replaced next month.
2.	prohibition	-	You are not to start working without antivirus prescan.
3.	necessity (the result of orders or instructions)	+ /?	You are to turn off the device at the end of work.
4.	unavoidable events	+ /?	What is to happen to the system?

Note:

Perfect infinitive after be to can express a planned or agreed action which didn’t happen.

Упражнение 7. Прочтите и переведите следующие предложения, обращая внимание на значение модального глагола beto и форму инфинитива после него:

1. An alternative way of expressing the instructions is to use mnemonic codes. 2. In industrial situations, the ability to inspect and, if necessary, reject quickly is desirable if further errors are to be prevented. 3. One of the main objectives of research and development in this field was to provide techniques and equipment capable of helping to control this “information explosion”. 4. An alternative to bit slice microprocessors for complex systems is to use several microprocessors together. 5. Zip drives are not to be confused with zip files.