một máy phát điện xoay chiều cho 1 hiệu điện thế ở 2 cực của máy là 2500V . Mốn tải điện đi xa người ta tăng hiệu điện thế lên 30000V bằng cách sử dụng 1 máy biến thế có số vòng dây cuộn sơ cấp là 2000 vòng 

a) tính số vòng dây của cuộn dây thứ cấp

b) khoảng cách từ nhà máy điện đến nơi tiêu thụ là 100km, công suất điện cần truyền laf300kw .tính công suất hao phí do tỏa nhiệt trên đường dây dẫn điện , biết mỗi km dây dẫn có điện trở là 0,2 Ω

Complete the sentences with the verbs in parentheses. Write if I + the past tense or the -ing form of the verb. In some sentences, either response is possible, but the meaning is different.

1.  A: It's cold in here. Would you mind (close) if I closing             the window?

B: Not at all. I'd be glad to.

2.  A: It's cold in here. Would you mind (close) if I closed     the window?

B: Not at all. Go right ahead. I think it's cold in here too.

3.  A: You're going to the library? Would you mind (take) if I taking         this book back to the library for me?

B: Not at all.

4.  A: I'm not feeling well at all. Would you mind (go) if I going    home now?

B: Oh, I'm sorry. I hope you can come back when you feel better.

5.   A: I'm not feeling well at all. Would you mind (leave) if I                    now before the visiting hours are over?

B: Oh, of course not. We shouldn't stay more than a short time for a hospital visit anyway.

6.   A: I'll be working late tonight, honey. Would you mind (cook)                   dinner tonight? I'll clean up after dinner.

B: I'd be happy to. About what time do you think you'll be home?

7.  A: We have a lot of chicken left over from dinner last night. Would you mind (make)

                          a chicken salad from the leftovers for dinner tonight? B: No, that'll be good. You make a great chicken salad.

8.  A: I'm feeling kind of worn out. Chopping wood in the hot sun is hard on me. Would you mind (finish)                                the work yourself?

B: No problem, Grandpa. Why don't you go in and rest? I'll finish up.

9.  A: Would you mind (use)                   your name as a reference on this job application?

B: Not at all. In fact, ask them to call me.

10.     A: I'd like to apply for the job as department manager. Would you mind (recommend)                                me to the boss?

B: No. As a matter of fact, I was thinking of recommending you myself.

Complete the sentences. Use the appropriate progressive forms of must, should, or may/might/could and the verbs in parentheses.

1.  A: Look. Those people who are coming in the door are carrying wet umbrellas.

B: It (rain)                             

2.  A: Why is Margaret in her room?

B: I don't know. She (do)                                      her homework.

3.  A: Do you smell smoke?

B: I sure do. Something (burn)                               in the kitchen.

4.  A: The line's been busy for over an hour. Who do you suppose Julio is talking to?

B: I don't  know. He (talk)                               to his parents. Or he (talk)

                              to his sister in Chicago.

5.  A: What's all that noise upstairs? It sounds like a herd of elephants.

B: The children (play)                               some kind of game. A: That's what it sounds like to me too. I'll go see.

6.  A: I need to call Howard. Do you know which hotel he's staying at in Boston?

B: Well, he (stay)                              at the Hilton, but I'm not sure. He (stay)

                              at the Holiday Inn.

7.  A: What are you doing?

B: I'm writing a letter to a friend, but I (study)                         I have a test tomorrow.

8.  A: Did you know that Majid just quit school and is hitchhiking to Alaska?

B: What? You (joke)                             

9.  A: Did Joe mean what he said about Majid yesterday?

B: I don't know. He (joke)                               when he said that, but who knows?

10.   A: Did Joe really mean what he said yesterday?

B: No, I don't think so. I think he (joke)                             

Complete the sentences with the verbs in parentheses. Write if I + the past tense or the -big form of the verb. In some sentences, either response is possible, but the meaning is different.

1.  A: It's cold in here. Would you mind (close)              the window?

B: Not at all. I'd be glad to.

2.  A: It's cold in here. Would you mind (close)     the window?

B: Not at all. Go right ahead. I think it's cold in here too.

3.  A: You're going to the library? Would you mind (take)          this book back to the library for me?

B: Not at all.

4.  A: I'm not feeling well at all. Would you mind (go)     home now?

B: Oh, I'm sorry. I hope you can come back when you feel better.

5.   A: I'm not feeling well at all. Would you mind (leave) if I                    now before the visiting hours are over?

B: Oh, of course not. We shouldn't stay more than a short time for a hospital visit anyway.

6.   A: I'll be working late tonight, honey. Would you mind (cook)                   dinner tonight? I'll clean up after dinner.

B: I'd be happy to. About what time do you think you'll be home?

7.  A: We have a lot of chicken left over from dinner last night. Would you mind (make)

                          a chicken salad from the leftovers for dinner tonight? B: No, that'll be good. You make a great chicken salad.

8.  A: I'm feeling kind of worn out. Chopping wood in the hot sun is hard on me. Would you mind (finish)                                the work yourself?

B: No problem, Grandpa. Why don't you go in and rest? I'll finish up.

9.  A: Would you mind (use)                   your name as a reference on this job application?

B: Not at all. In fact, ask them to call me.

10.     A: I'd like to apply for the job as department manager. Would you mind (recommend)                                me to the boss?

B: No. As a matter of fact, I was thinking of recommending you myself.