A, B, C là ba điểm tạo thành tam giác vuông tại A đặt trong điện trường đều có E → / / B A →  như hình vẽ. Cho α = 60 ° ; BC = 10cm và  U B C = 400V.

a) Tính  U A C , U B A và E.

b) Tính công lực điện trường khi dịch chuyển điện tích q =  10 - 9 C từ A đến B, từ B đến C và từ A đến C.

c) Đặt thêm ở C một điện tích điểm  q 0 = 9. 10 - 10 C. Tìm cường độ điện trường tổng hợp tại A.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

Do you ever wish you were more optimistic, someone who always (45)____ to be successful? Having someone around who always fears the worst isn't really a lot of (46)____ - we all know someone who sees a single cloud on a sunny day and says, 'It looks like rain.' But if you catch yourself thinking such things, it's important to do something about it.

You can change your view of life, according to psychologist. It only takes a little (47)___, and you'll find life more rewarding as a (48)____. Optimism, they say, is partly about self-respect and confidence but it's also a more positive way of looking at life and all it has to (49)____. Optimists are more (50)_____ to start new projects and are generally more prepared to take risks.

Upbringing is obviously very important in forming your (51)___ to the world. Some people are brought up to depend too much on others and grow up forever blaming other people when anything (52)____ wrong. Most optimists, on the (53)____ hand, have been brought up not to (54)____ failure as the end of the world - they just get on with their lives.

Điền vào ô 50

A. possible

B. likely

C. hopeful

D. welcome

Chọn dạng đúng của từ trong ngoặc:

1. Steel is very .useful... for building ( use)

2. She knows all the people in her .neighborhood... ( neighbor)

3. Lan and Hoa go to the public library.regularly... very Sunday evening.(regular)

4. He had an accident although he drove..carelessly.. ( care)

5. Playing video games is on kind of..amusement.. (amuse)

6. The children are always.noisy...(noise)

7. When being a child, she received a good.education...(educate)

8. What a ..boring.. party!( bore)

1. There is .................... fuit juice in the bottle. (some / any / a / an)

2. She is thirsty. She'd like .................... drink. (any / a / an / some)

3. Would you like .................... chicken? (a / an / some / any)

4. Are they going to see .................... in Ha Noi. (Cham museum / the citadel / Ngoc Son Temple / Huong Pagoda)

5. We .................... dinner at home every day. (Has / have / are having / is having)

6. .................... you going to visit Hue this Summer? (Do / Does / Are / Is)

7. There is .................... water in the bottle (some / any / a / an)