Change the following sentences into  the passive voice.

1. The teacher corrects our homework every day.

2. The librarian doesn’t allow me to take the book home.

3.  They are building a new hospital in Ha Tinh City.

4. You should submit this application form right now.

5. He has to finish the report before the fifth of the month.

6. No one has used this sewing machine for several months.

7. The children are drawing pictures about their ideal world.

8. They awarded him the Nobel Prize for medicine in 1946.

9. We saw him leave the office at 6 o’clock this morning.

10. You ought to water these plants once a week.

11. People saw her driving a car near the bridge.

12. They said that he was the richest man in the town. 

13. Scientists began to carry out researches on AIDS in 1981.

14. Everybody believed that he had died of lung cancer.

15. People can’t learn a foreign language in a short time.

16. Did anyone ask any questions about me ?

17. The robbers forced the bank manager to hand over the money.

18. They let us go.

19. Some people think he is a dangerous criminal.

20. No one told me the truth.

Cho biểu thức:
\(C=\dfrac{\sqrt{x}-2}{\sqrt{x}-1}-\dfrac{\sqrt{x}+2}{\sqrt{x}-2}+\dfrac{6\sqrt{x}-8}{x-3\sqrt{x}+2}\)

với x ≥ 0 , x ≠ 1 , x ≠ 4

a. Rút gọn C

b. Tính C khi x = 36

Cho biểu thức:
\(B=\left(\dfrac{3}{\sqrt{x}+2}-\dfrac{1}{\sqrt{x}-2}\right):\left(\dfrac{\sqrt{x}-6}{x-2\sqrt{x}}+\dfrac{1}{\sqrt{x}}\right)\)

với x > 0 , x ≠ 4

a. Rút gọn B

b. Tìm x để B = 1/3

Cho biểu thức
\(A=\left(\dfrac{1}{\sqrt{x}-3}+\dfrac{1}{\sqrt{x}+3}\right)\left(1-\dfrac{3}{\sqrt{x}}\right)\)

với x > 0 và x ≠ 9

a. Rút gọn A

b. Tìm x để A > 1/2

Cho tam giác ABC . Có góc B = 40 độ , góc C = 35 độ , BC = 20cm . tính AC

Cho hình thang ABCD có góc A = góc D = 90 độ . AD = 77 cm , AB = 91 cm , DC = 127 cm . 

a. Tính diện tích hình thang ABCD
b. Tính góc C và BC

Cho hình vẽ : 

AC = 10 cm

a . Tính AB , BC

b. Tính góc D