I). Change thế sentences into pasive.

  1. Peter is writing a letter to his friend

   2. My friends making some phone calls in the evening.

    3. B ad drivers are causing many accidents

    4. The children are  eating a lot of sweets

   5. Nam is repairing mt piano at the moment

   6. They are demolishing the entire block

   7. Someone is cutting the glass now

   8 The factory is producing more and more pollution

9 Someone is showing her now to do it

10 The boys are plantting some trees in the garden

11 Lan was prepairing that report when i came to see him

12. waiters and waitresses were serving customers

13. The president was signgs those papers

14. Was mary helping her mother in the kitchen at the time?

15. The head teacher was making the announcement

16 Someone was cleaning the windows while I was there

17 They sere preseting the athletes to the spectators when we came

18 Someone is making the coffee when I walk into the kitchen

19 They have sold their car to pay debts

20 No one has opened the windows for ages

21 No one has over asked me that question before

22 They haven't done anything since he left

23 A doctor has just examined Jonh

24 They haven't used this machine for ages

25 Peter has sung this song

26 They have paid doctor a lot of money 

Dùng cách nào  sau đây để phân biêt 3 chất khí không màu đựng trong 3 lọ riêng biêt: CO₂, O₂, H₂

A.Tàn đóm               B. Nước                    C. Quỳ tím                            D. CuO, nung nóng