Phân tử hợp chất A gồm 1 nguyên tử của nguyên tố X liên kết với 4 nguyên tử Hidro; trong hợp chất A, X chiếm 75%. Xác định công thức hóa học của hợp chất A. 

 Phân tử của hợp chất A gồm 1 nguyên tử của nguyên tố R liên kết với 2 nguyên tử oxi. Biết trong phân tử A, oxi chiếm 50% về khối lượng. Xác định KHHH của nguyên tố R

Phân tử của hợp chất A được tạo nên từ 2 nguyên tử của nguyên tố R liên kết với 3 nguyên tử oxi. Phân tử khối của A gấp 5 lần nguyên tử khối của lưu huỳnh. Xác định CTHH của hợp chất A

Hợp chất X được tạo ra từ 2 nguyên tử R và 5 nguyên tử O có phân tử khối là 142 đvC. R có nguyên tử khối là bao nhiêu?

tính chất cơ học, vật lí, hoá học và công nghệ tính chát nào quan trọng nhất? vì sao?

I.            Choose the word whose underlined part is pronounced differently from the others :

1.      A. application              B. nation                           C. bank                            D. paper

2.      A. over                       B. enroll                            C. program                       D. hobby

3.      A. usually                    B. used                             C. unite                            D. voluntary

4.      A. certainly                  B. aim                              C. mainly                          D. raise

5.      A. friend                     B. handicap                       C. tidy                              D. education

6.      A. character                 B. act                               C. land                             D. similar

7.      A. fitness                    B. differ                            C. establish                       D. tidy

8.      A. voluntary                B. along                            C. support                        D. organizing

9.      A. resource                 B. your                             C. course                          D. encourage

10.    A. hobbies                  B. bags                            C. groups                          D. organizations  

1.      I used (smoke) ___________ 20 cigarettes a day, but he has given up (smoke) _____.

2.      Stop (argue) __________________ and start (work) ___________________.

3.      Did you remember (turn) __________ off the lights when (go) _________________ out.

4.      I remember (meet) ___________________ you before.

5.      You’ll be able (do) ___________________ yourself when you are older.

6.      We began (talk) ________________ about next year’s holiday two weeks ago.

7.      I finished (read) _________________ the book and went to bed.

8.      You seem (know) ____________ this area well. – Yes, I am used (live) __________.

9.      I am looking forward to (see) _________________ good response from your company.

10.   I hate (look after) _________________ a crying child.

She always practices (score) ____________ by (shoot) ___________ some 

I.            Use the correct form of the verb : GERUND or INFINITIVE :

1.      Children enjoy (read) __________________ comics and picture books.

2.      My younger brother is afraid of (stay) __________________ at home alone.

3.      He used to (take) ____________________ a bus to his office.

4.      She intends (spend) ____________________ her summer holiday in Spain.

5.      My brother wants (take) ___________________ a trip next week.

6.      Lan should (go) ____________________ to bed early.

7.      We dislikes (repeat) ____________________ poems.

8.      It is very sad (stay) ___________________ at home at weekends. (stay)

9.      We decided (rent) __________________ a house having a swimming pool.

10.   I used (smoke) ___________ 20 cigarettes a day, but he has given up (smoke) _____.

I.            Use the correct form of the verb : GERUND or INFINITIVE :

1.      Children enjoy (read) __________________ comics and picture books.

2.      My younger brother is afraid of (stay) __________________ at home alone.

3.      He used to (take) ____________________ a bus to his office.

4.      She intends (spend) ____________________ her summer holiday in Spain.

5.      My brother wants (take) ___________________ a trip next week.

6.      Lan should (go) ____________________ to bed early.

7.      We dislikes (repeat) ____________________ poems.

8.      It is very sad (stay) ___________________ at home at weekends. (stay)

9.      We decided (rent) __________________ a house having a swimming pool.

10.   I used (smoke) ___________ 20 cigarettes a day, but he has given up (smoke) _____.

11.   Stop (argue) __________________ and start (work) ___________________.

12.   Did you remember (turn) __________ off the lights when (go) _________________ out.

13.   I remember (meet) ___________________ you before.

14.   You’ll be able (do) ___________________ yourself when you are older.

15.   We began (talk) ________________ about next year’s holiday two weeks ago.

16.   I finished (read) _________________ the book and went to bed.

17.   You seem (know) ____________ this area well. – Yes, I am used (live) __________.

18.   I am looking forward to (see) _________________ good response from your company.

19.   I hate (look after) _________________ a crying child.

20.   She always practices (score) ____________ by (shoot) ___________ some hoops.

21.   Are you free now ? No, I am busy (tidy) __________________ my bedroom.

22.   I suggest (go) ___________________ on a day-trip to the countryside on the weekend.

23.   Can you help me (fix) _____ the energy-saving bulb because it helps (save) _______ energy.

24.   It is very interesting (join) _____________________ in the Y & Y club.

25.   Could you (do) ________________ me a favor ?

26.   He joins the Y & Y club because he likes (take) _____________ part in social activities.

27.   Please give the form to your teacher and ask her (sign) __________________ in it.

28.   I don’t mind (travel) _________________ by train.

29.   I am very fond of (visit) _________________ other countries.

30.   Have you finished (clean) ___________________ the kitchen yet ?

31.   Good bye. I hope (see) __________________ you soon.

32.   You must stop (work) __________________ hard. It is bad for you.

33.   The weather is very nice, so I suggest (go) _________________ for a walk.

34.   I am tired. I would like (go) _________________ to bed.

35.   I am trying (finish) ___________________ my work. Please stop (talk) _________________.

36.   They were very angry and refused (talk) _________________ to us.

37.   We invited Ann to the party, but she didn’t want (come) __________________.

38.   I went (hike) ____________________ with some friends in Chau Thoi Mountain.

39.   Don’t forget (send) ______________ me a postcard when you have arrived there.

40.   I like (think) ________ about things carefully before (make) __________________ a decision.

41.   Don’t try (persuade) __________ me. Nothing can make me (change) ___________ my mind.

42.   I prefer (walk) _________________ to (drive) ______________________.

43.   Don’t forget (lock) ________________ the door before (go) _________________ to bed.

44.   Does your jacket need (wash) ____________ ? ~ No, but you need (iron) ________________ it.

45.   Did you succeed in (solve) _______ the problem ? Let me (suggest) _______ some solutions.

46.   Ask him (come) _________ in. Don’t keep him (stand) _________________ at the door.

47.   It was a really good holiday. I really enjoyed (be) _________________ by the sea again.

48.   I don’t mind (walk) __________________ home, but I’d rather (get) ________________ a taxi.

49.   Uncle Ho devoted his life (gain) _________________ the independence for our country.

50.   The youth can participate in different programs such as (raise) _______________ funds for the poor and (plant) ________________ trees along the sidewalk.