Răng được bảo vệ bởi lớp men cứng, dày khoảng 2mm. Lớp men này là hợp chất Ca5(PO4)3OH và được tạo thành bằng phản ứng:

5Ca2+ + 3PO43- + OH- → Ca5(PO4)3OH (1)

II. Change into passive

6. They didn’t invite me to the birthday party.=> __________________
7. they built that house in 1972 =>_________________________________
8. Mr. Smith has taught us French for two year.
9. They didn’t look after the children properly.
10. Nobody swept this street last week.

III. Rewrite sentences with: although/ despite
1. She felt sick. She went to work. (though) =>
2. I was really tired. I couldn’t sleep. (even though) =>
3. He is very rich. He isn’t happy. (although) =>
4. She couldn’t answer the question. She is very intelligent. (though) =>
5. He tried. He was not successful. (though) =>
6. His life is hard. He determined to study well. =>

chúc mừng các bn

1 were walking

2 was enjoying

3 was taking

4 were playing

5 was vaccuming

6 were painting

7 Were he resting

8 was reading

câu hỏi đâu bn

mik đúng rồi à

ai đúng zậy

1.B

2.D

3.D

4.D

5.B

1.A

2.A

3.D

4.A

5.B

6.B

7.C

8.B

9.A

10.B