Из вершин А и D правильного тетраэдра ABCD одновременно и с одной скоростью стали двигаться по рёбрам АС и DB точки X и Y. Докажите,

1 How often do you go to the cinema? (do…go – Present Simple, to go)

2 Usually Tom sleeps well,but last night he slept badly. (sleeps - Present Simple, to sleep) (slept - Past Simple, to sleep)

3 When did you write your composition? (did…write - Past Simple, to write)

4.The River Amazon flows into the Pacific Ocean. (flows - Present Simple, to flow)

5.I shall go to the party tomorrow night,will you come with me? (shall go - Future Simple, to go) (will come - Future Simple, to come)

6.Look!It is snowing. (is snowing – Present Continuous, to snow)

7.What were they doing at 10.30?-They were having breakfast. (were doing - Past Continuous, to do) (were having - Past Continuous, to have)

8.Don't come at 5.I shall be writing a composition. (shall be writing – Future Continuous, to write)

9.When she came,the children were sitting in the sitting room and watching TV. (came – Pst Simple, to come (were sitting and watching – Past Continuous, to sit, to watch)