Tìm x biết:

a, x^3 - 16x = 0

b, ( x -1 ) ( x + 2 ) - x - 2 = 0

c, 2 ( x +3 ) - x ( x + 3 ) = 0

Thì bị động của câu hỏi. Đổi sang câu bị động:

1: Did your friend mail that letter ?

2: Has Nina finished the work?

3: Did he speak about tropical countries in the world?

4: Had your sister cleaned the floor when I came ?

5: Does he make bad chocolate cake?

6: Must you post this letter?

7: Have you taken my book?

8: Can you clean the house?

9: Does he steal my ruler ?

10: Does your friend buy this house

Thì hiện tài hoàn thành . Đổi sang câu chủ động

1. These newspapers have been bought by Nina

2. These reports have been typed for 2 hours

3. My dogs have been taken good care of by my father

4. Computer science has been studied by my brother since June

5. This movie hasn't been seen by my mother

6. This car has been bought bt Nina

7. The thief has been found by the police

8. Her pens have been found

9. The reports have been fonished

10. These pencil cases have been bought by Nina