Turn from ACTIVE into PASSIVE: 

21.He has to pay the bill. ........................................................

22.For the time being, Alice is teaching that group. ........................................................

23. She has finished the report. ........................................................

24.The police have arrested five suspects. ........................................................

25.The mad dog bit the little boy.

26.The teacher corrects our exercises. ........................................................

27.Mr. Smith saw the accident. ........................................................

28.They started a dancing class last week. ........................................................

29.You should insure the package. ........................................................

30.He may pay the bill for us. ........................................................

31.You ought to water the plants once a week. ........................................................

32.The mailman is delivering the mail now. ........................................................

33.Somebody has taken my briefcase. ........................................................

34.The doctor ordered him to take a long rest. ........................................................

35.Lightning struck the house. ........................................................

36. When will you do the work? ........................................................

37 How are you going to deal with this problem? ........................................................

38. How do you spend this amount of money? ........................................................

39. I wonder whether the board of directors will choose Susan or Jane for the position. ........................................................

40. How did the police find the lost man? ........................................................

Cho tam giác ABC, các tia phân giác góc B, C cắt nhau tại I. Qua I kẻ đường thẳng song song với BC cắt AB và AC lần lượt tại D và E.

a, Tìm các hình bình hành có trong hình.

b, Chứng minh rằng: tam giác BID cân ở D và tam giác IEC cân ở E.

c, So sánh DE với tổng BD+CE.