1. He said he didn’t know what had happened.

2. She said that she had gone to the dentist yesterday.

3. She said the doctor had written her a prescription.

4. He said that he had a toothache.

5. She said she went to the museum every day.

6. They said they were going to the supermarket.

7. She said that the doctor had given her some pills.

8. He said he had received the report.

9. They said they had visited the aquarium.

10. He said that he was feeling sick.

11. She said she had bought some bread.

12. He said that he was turning off the television.

13. They said they were driving to Chicago.

14. She said she would write him a prescription.

15. They said they were going to the drugstore.

16. He said that the doctor had given him some pills.

17. She said that she went to the supermarket everyday.

18. He said he had received the envelope.

19. They said that they had visited Cannery Row.

20. She said that she felt very sick.

21. He said he had bought some popcorn.

22. They said they were flying to California.

23. He said he was cutting off the main valve.

24. He said he didn’t know what had happened.

25. She said that she had gone to the doctor yesterday.

26. He said he had a toothache.

27. He said he didn’t know what had happened.

28. She said that she had gone to the dentist yesterday.

29. She said the doctor had written her a prescription.

30. He said that he had a toothache.

31. She said she went to the museum every day.

32. They said they were going to the supermarket.

33. She said that the doctor had given her some pills.

34. He said he had received the report.

35. They said they had visited the aquarium.

36. He said that he was feeling sick.

37. She said she had bought some bread.

38. He said that he was turning off the television.

39. They said they were driving to Chicago.

40. Mary said, she didn’t know why the car had hit her.

31 the roads were crowded with refugees. many of them were wounded

\(\sqrt{2x-2\sqrt{2x-1}}=1\)

\(\sqrt{x+2\sqrt{x-1}}=2\)

tìm x

cho 0,54 gam bột al vào 20gam dd A sau khi pu kết thúc lọc tách được m gam chất rắn

tính m

ngtu ngto A có Tổng số hạt n, p, e của một nguyên tử là 34. Số hạt mang điện nhiều hơn hạt không mang điện là 1

xác định nguyên tố A

đốt cháy 1,35 gam bột al hoàn toàn trong bình đựng 672ml khí oxi tính % khối lượng mỗi chất rắn thu được trong hỗn hợp sau phản ứng

Cho 115,3 g hỗn hợp 2 muối MgCO3 và RCO3 vào dung dịch H2SO4 loãng thu được 4,48 lít khí CO2 (đkc), chất rắn X và dung dịch Y chứa 12 gam muối. Nung X đến khối lượng không đổi, thu được chất rắn Z và 11,2 lít khí CO2 (đkc). Khối lượng của Z là: