阅读理解。
I'm 14, a year younger than most of my classmates.
A week ago one of my classmates, Nitin, asked me for help with math homework. We ended up
talking about computers and file-sharing (共享文件). As we talked I found that he was more experienced
and could teach me about file-sharing and networking. We went to his room and watched a movie about
robots that he'd downloaded. The math homework was forgotten.
The next day he came again for homework help "What do you do on weekends?" he asked. The truth
is, when I have work to do, I do it. I have no special time to kill with friends. I was embarrassed about
this. I expected him to think I was boring and said, "Get a life!" He said, "OK. You're 
having trouble
getting along with people I can show you. I'm old than you."
Later, he checked my computer. He even connected me to an Internet chess server (服务器). He was
becoming like a big brother.
But when I thought about it, I didn't really want Nitin's help" His big-brother idea began to bore me.
"I'll get you some cool computer programs (程序)".
"I'll teach you how to talk to girls."
He meant what he was saying, but I don't know why it didn't make me feel good. Since then he's
hardly talked to me; we seem to have forgotten each other. I don't think he can "teach" me much, and I
don't think much of him. But I could be wrong?
1. What did Nitin help me do?
A. He helped me with my homework.
B. He helped me with math problems.
C. He taught me about file-sharing and networking.
D. He introduced some fiends to me.
2. What does the underlined word "kill" in Paragraph 3 mean?
A. 杀死
B. 浪费
C. 消磨 (时间)
D. 打猎
3. Which is NOT the reason why the writer doesn't want Nitin's help?
A. He has no special time to kill with friends.
B. He forgot his homework because of playing with him.
C. He thinks his ideas are not useful to him.
D. He has another big brother.
4. Can you use a word to describe the writer?
A. Unfriendly.
B. Boring.
C. Independent. (独立的)
D. Lazy.
5. Choose a title for this passage.
A. I Don't Want a Big Brother!
B. No Time to Kill
C. My Big Brother
D. My Life After School
V
W
,然后根据
可得：
,A错误，
,B错误
，所以该交流电的频率为：
,交流电在一秒内电流方向改变次数为
，D错误，C正确