15. Before I watch I do my homework.
16. She likes cooking. She is cooking now.
17. She has learns piano for three months.
18. I received a letter from my old friend last week.
19. She washes cloth twice a week.
20. We do exercise 2A on page 20 right now.
21. Look! It is raining heavily.
22. After they go,I sit down and rest.
23. They watched TV at 4:00 p.m yesterday.
24. He opened the door, entered the room, and broke something.
25. After I washed my clothes, I had slept.