.Use "must," "to have" or "to be":
1. The train ... arrive in five minutes, we... hurry up. 2. If he doesn't meet you at the station you... take a taxi. 3. They be here an hour ago. 4.1... go to the library after classes because I... make a report tomorrow. 5. It ... be a very interesting novel, I know the author. 6. I don't think you ... wait long. 7. They... marry early in June, so they... stay in Moscow. 8. She ... clean her shoes after working in the garden. 9. The lecture... begin in a minute. 10. You... be tired, you... have a little rest. 11. I.. answer a lot of questions at the examination. 12. We ... leave on Monday.

1. The train must arrive in five minutes, we must hurry up.
- The word "must" is used to express a high degree of certainty or necessity. In this sentence, it implies that it is necessary for the train to arrive in five minutes in order for us to hurry up.

2. If he doesn't meet you at the station, you must take a taxi.
- The word "must" is used to express a high degree of necessity. In this sentence, it implies that if he doesn't meet you at the station, it is necessary for you to take a taxi.

3. They should have been here an hour ago.
- The phrase "should have been" is used to express an expected or recommended action that did not happen. In this sentence, it implies that they were expected to be here an hour ago, but they have not arrived yet.

4. I have to go to the library after classes because I have to make a report tomorrow.
- The phrase "have to" is used to express an obligation or a necessity. In this sentence, it implies that it is necessary for me to go to the library after classes in order to make a report tomorrow.

5. It must be a very interesting novel, I know the author.
- The word "must" is used to express a high degree of certainty. In this sentence, it implies that I am certain that the novel is very interesting because I know the author.

6. I don't think you have to wait long.
- The phrase "have to" is used to express a necessity or obligation. In this sentence, it implies that I don't believe it is necessary for you to wait for a long time.

7. They are going to marry early in June, so they will have to stay in Moscow.
- The phrase "will have to" is used to express a future obligation or necessity. In this sentence, it implies that because they are getting married early in June, it will be necessary for them to stay in Moscow.

8. She has to clean her shoes after working in the garden.
- The phrase "has to" is used to express an obligation or necessity. In this sentence, it implies that it is necessary for her to clean her shoes after working in the garden.

9. The lecture is going to begin in a minute.
- The phrase "is going to" is used to express a future event or action. In this sentence, it implies that the lecture will start very soon.

10. You may be tired, you can have a little rest.
- The words "may" and "can" are used to express permission or possibility. In this sentence, it implies that it is possible for you to be tired, and you are allowed to have a little rest.

11. I have to answer a lot of questions at the examination.
- The phrase "have to" is used to express an obligation or necessity. In this sentence, it implies that it is necessary for me to answer a lot of questions during the examination.

12. We have to leave on Monday.
- The phrase "have to" is used to express an obligation or necessity. In this sentence, it implies that it is necessary for us to leave on Monday.