Ответ:

1) What colour is the dog?

2) The dog is black.

3) The letter was from my friend.

4) I was at the party organised by my friend.

5) He saw the woman who lived next door to him.

6) He entered the door nearest to the stairs.

7) I go to the school.

8) Today it is a school concert so all our family will go to the school.

9) They have never been to the theatre.

10) We go to the cinema every weekend.

11) I closed the door and opened the window.

12) The floor was clean.

13) Where is the railway station?

14) The city hall is very old.

15) The market was crowded in the morning.

16) I need to go to the bank tomorrow.

17) Tom went to the post office to send a letter.

18) You should go to the doctor.

19) She is seeing the dentist on Friday.

20) The cats don't let me sleep!