（）的服务半径大于1000km，依靠电离层对天波的反射完成电波传播

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问题单项选择题

（）的服务半径大于1000km，依靠电离层对天波的反射完成电波传播，多用垂直天线，该天线在水平面与垂直面均有较强的方向性。

A.短波广播

B.长波广播

C.GSM基站

D.CDMA基站

答案

参考答案：A

填空题

用所给词的正确形式填空。

1. She said she (watch) TV at this time yesterday.

2. I think I________(stay) at home tomorrow.

3. He invited her ________(dance)for me.

4. My sister would like________ (be) a movie star.

5. I'm against ________ (stay) here. We must go now.

6. I think there will be ________ (little) pollution in ten years.

7. If it (not rain), we'll go to the park tomorrow.

8. While the alien was _________ (visit) the museum, the boy called the TV station.

9. In English, I'm ________ (good) at reading than listening.

10. For many young people, becoming a ________ (profession) athlete seems like a dream job.

单项选择题

分配阀的紧急放风阀两个排风堵装错或堵塞会造成：（）。

A、大闸制动区时列车管不排风

B、大闸制动区时，起紧急制动