Trong tự nhiên clo có hai đồng vị bền:$C{l}_{17}^{37}$ chiếm 24,23% tổng số nguyên tử, còn lại là $C{l}_{17}^{35}$. Thành phần phần trăm theo khối lượng của $C{l}_{17}^{35}$trong HClO4 là

III.Rewrite the sentences using the words given without changing their meaning

1. I didn't go to school because I was sick.

-> I was sick, so __i didn`t go to school.____________________________________________

2. It will be good if you eat less meat and more vegetables.

->You should ___eat less meat and more vegetables__._________________________________________

3.  July stayed home from school yesterday because she had a high fever.

→ July had a high fever,  _so July stayed home from school yesterday_.____________________________________________

4.  She eats fruits and veggies every day, but she keeps gaining weight.

→ Although __ She eats fruits and veggies every day, but she keeps gaining weight.___________

5.  It’s a good idea to do exercise regularly. (should)       

→ You ___should __ to do exercise regularly _._________

6. We suggest watching the latest films. (what)

=> ________________________

7. Let's go to the movie theatre? (How)

=> ________________________

8.The last time I watered this tree was a week ago.

=> I haven't __watering this tree for a week.___________________________

9. My younger brother last went to the zoo when he was 10.

=> My younger brother _has gone to the zoo since he was 10.________________________________

10. We have learned English for 10 years.

=> We started _learning English in 10 years.______________________________________________________________.

11. Ms. Ann hasn’t taken part in any voluntary programs for 4 years.

=> Ms.Ann last __taking part in any voluntary prgrams 4 years ago.____________________________________________________________.

12. She started to live in Hanoi 2 years ago.
→ She has __started to live in Hanoi for 2 years._________________________
13. He began to study English when he was young.
→ He has __begun to study English since he was young._________________________
14. I started studying English 3 years ago.

=> I have __studyed English for 3 years.____________________________

15. She has worked for that organization for a month.

=> She stared ____working for that organization last month.__________________________
16. She last had a swim 5 years ago.

=> She hasn't _swam for 5 years._____________________

17. I haven't been Hanoi for 2 years.

=> The last time ___i be Hanoi 2 years ago._____________

18. We have donated books and clothes for ten years.

=> We began_donating bools and clothes 10 years ago.___________________________________________.

19. I haven't heard him since August.

=> The last time __i hearding him last August._____________________

20. He hasn’t smoked for 2 years.

=> The last time he smoking 2years ago. __________________________

20 điểm

Cho ba đường thẳng (d1) : y = x + 2 ; (d2) : y = -x - 2 và (d3) : y = -2x + 2. 

a) Vẽ ba đồ thị hàm số trên cùng một hệ trục tọa độ. 

b) Cho (d1) cắt (d2) tại A, (d1) cắt (d3) tại B, (d3) cắt (d2) tại C. Tính S tam giác ABC. 

Chon câu thành ngữ , tục ngữ không cùng nghĩa

a.Đồng cam cộng khổ

b.đồng sức đồn lòng

c.chung lưng đấu cật

d.Bằng mặt nhưng không bằng lòng