Từ thông xuyên qua một vòng dây của cuộn sơ cấp máy biến áp lí tưởng có dạng:  ϕ = 2 cos 100 π t   ( m W b ) . Cuộn thứ cấp của máy biến áp có 1000 vòng. Biểu thức suất điện động ở cuộn thứ cấp là:

A.  e = 200 π cos 100 π t   ( V )

B.  e = 200 π c o s 100 π t − 0 , 5 π   ( V )

C.  e = 100 π cos 100 π t − 0 , 5 π   ( V )

D.  e = 100 π cos 100 π t   ( V )

1. Verb forms - Verbs tenses:

1. Water boils at the 100^oC.

2. The moon moves around the Earth.

3. Hoa received a letter from Nien yesterday.

4. She wasn't old enough to be in my class.

5. The film finishes at 9 o'clock.

6. I usually spend my freetime reading books.

7. The sun sets in the West.

8. He enjoys doing volunteer work at a local orphanage.

9. We got married in the 2002.

10. Nam, I would like you to meet my cousin.

11. What does he look like?

12. My father always drinks coffee in the morning.

13. Vegetarians don't eat meats.

14. Ms Lien has long black hair.

15. She lived in Hue when she was 15.

16. Ba's jokes sometimes annoy his friends.

17. Tam is sociable and helpful.

18. Why don't you join our English speaking club?

19. It's a pleasure to meet you, Mrs Vi.

1. This red car is 50000 and that blue car is 50000, too. Oh! It's expensive.

=> That car is the same price as this car.

2. Da Nang is very large and it's more beautiful than my hometown.

=> My hometown is not as beautiful as Da Nang.

3. That green ball is big but my ball is too small.

=> My ball is different from that green ball.

2. Make the complete sentences using the cues given.
1. They cried when they heard the bad news.
2. I used to live with my grandmother when I was a child.
3. I wish I knew many people in this town.
4. He was watching TV when the phone rang.
5. While I was looking for my passport, I found the old photographs with my family.
6. The boys were playing cards when the police came.
7. We have lived here since 1986.
8. While the guests were dancing, the thieves broke into the house.
9. I wish I were rich.
10. They were walking in the park when it rained.
3. Choose the underlined word or phrase (marked A, B, C or D) in each sentence that need correcting.
1. B (can help => could help)
2. B (see => saw)
3. D (pay => paying)
4. D (didn't phone => haven't phoned)
5. C (go => would go)
6. C (will work => works)
7. C (so => because)
8. B (worked => were working)
9. B (painting => painted)
10. C (getting => get)

Một vật có khối lượng 400 g dao động điều hìa có đồ thị động năng theo thời gian như hình vẽ bên. Tại thời điểm t 0 = 0 vật đang chuyển động theo chiều dương. Lấy π 2 = 10  phương trình dao động của vật là:

A.  x = 10 cos π t − π 6 c m

B.  x = 10 cos 2 π t − π 3 c m

C.  x = 5 cos 2 π t − π 3 c m

D.  x = 5 cos π t − π 3 c m

Cho hình vẽ mô tả thí nghiệm điều chế dung dịch X:

Dung dịch X đặc nguội có thể tham gia phản ứng oxi hóa - khử được với bao nhiêu chất trong số các chất sau: CaCO₃, Fe(OH)₂, Fe₂O₃, Cu, FeS₂, Fe, Cr, Fe(NO₃)₂, Al, Ag, Fe₃O₄ ?

A. 6

B. 4

C. 5

D. 7