问题 填空题

无线局域网采用的扩频方法主要是跳频扩频与______扩频。

答案

参考答案:直接序列

解析: 目前,最普遍的无线局域网技术是扩展频谱技术。无线局域网采用的扩频方法主要有跳频扩频和直接序列扩频。

阅读理解

I have returned to my hometown after I was away ten years ago. So many things have changed around here. It has become better and better. When I left here, there was a small pool on the right of my house. Now the pool has gone and people have built a large shopping mall(商场) there.

The biggest changes have taken place in the center of the city. There are sidewalks on both sides of the street. You can see a street center with so many tall buildings around. You can’t drive there any more because no vehicle is allowed to pass there. A European-style fountain(喷泉) has been built in the street center garden.

There used to be an old school near my house. I spent my five years studying there. There was a small payground in front of the school. But now what I can see are five tall buildings standing there. There are two big classroom buildings and a library. A new post office has also been built just across from the new school.

小题1:I have been away from my hometown for ________.

A.ten months

B.one year

C.five years

D.ten years小题2:On the right of my house, there was a _________ ten years ago.

A.library

B.garden

C.supermarket

D.pool小题3:No vehicle is allowed to pass the _________.

A.center of the city

B.old school

C.street center

D.playground小题4:Which of the following is WRONG(错的)?

A.A fountain is in the street center garden.

B.Now there is an old school near my house.

C.There are two big classroom buildings and a library in the new school.

D.There is a post office across from the school.小题5:What’s the best title for the passage?

A.Great Changes in My Hometown.

B.A Wonderful Place

C.What a Nice Town

D.My School.

多项选择题