Use the correct tense-forms.
1. - When the plane (to leave)?
- The plane (to take off) in ten minutes.
2. Last year we spend our holidays in Sochi. The weather (to be) fine. We (to swim) and (to sunbathe) a lot.
3. The plant (to be going) to produce a new modal of equipment. We hope the model (to be) in great demand.
4. I just (to look through) the morning mail and now I (to be going) to send some faxes.
5. The accommodation at the English seaside (to become) very expensive recently.
6. The manager (to answer) the mail now. He always (to work) with the mail in the morning.
7. – You often (to spend) your holidays at the seaside?
- No, I…. I (not to be) to the seaside for some years.
8. When I (to arrive) in London, it (to rain) heavily.

1. - When does the plane leave?
- The plane takes off in ten minutes.

In this case, we use the present simple tense for the first question because it refers to a future action that is scheduled or planned. The answer uses the future simple tense because it describes a future action.

2. Last year we spent our holidays in Sochi. The weather was fine. We swam and sunbathed a lot.

In this case, we use the past simple tense because it refers to actions that took place in the past. The verbs "spent," "was," "swam," and "sunbathed" are in the past simple tense.

3. The plant is going to produce a new model of equipment. We hope the model will be in great demand.

In this case, we use the present continuous tense for the first sentence because it refers to a plan or arrangement for the future. The second sentence uses the future simple tense to express a possibility or expectation in the future.

4. I have just looked through the morning mail and now I am going to send some faxes.

In this case, we use the present perfect tense for the first sentence because it describes an action that happened in the recent past and has a connection to the present. The second sentence uses the future continuous tense to describe a future action that is planned or intended.

5. The accommodation at the English seaside has become very expensive recently.

In this case, we use the present perfect tense because it describes a change or development that has happened recently and still has an effect in the present.

6. The manager is answering the mail now. He always works with the mail in the morning.

In this case, we use the present continuous tense for the first sentence because it describes an action that is happening at the moment of speaking. The second sentence uses the present simple tense to describe a habitual action.

7. - Do you often spend your holidays at the seaside?
- No, I haven't been to the seaside for some years.

In this case, we use the present simple tense for the first question because it refers to a general habit or recurring action. The second sentence uses the present perfect tense because it describes an action that started in the past and has a connection to the present.

8. When I arrived in London, it was raining heavily.

In this case, we use the past simple tense for both sentences because they describe actions that took place in the past.