设m=ABCDEF，下列表达式不能得到DEF的是（）.A.Right$（m，3） B

阅读理解。

     We are learning English, but how can we learn English well? A student can know a lot about English,

but maybe he can't speak English.

     If you want to know how to swim, you must get into the river and practice a lot. And if you want to be

a football player, you must play football regularly.

     So you see, you can learn by using it. You must listen to your teacher in class. You should' speak English

to your classmates every day and also you should have the good habit of keeping diaries in English. Then one

day you may find your English very good.

1. You know a lot about English, but maybe ______ it.

A. you can speak

B. you can study

C. you can't speak

D. you can't study

2. You must get into the water ______.

A. to learn how to swim

B. to skate

C. to jump

D. to play

3. Do you want to be a football player? Please ______.

A. buy a football

B. play football

C. have some lessons

D. read some books

4. If you want to study English well, you should often ______.

A. speak English to your classmates

B. write something in English

C. listen to your teacher in class

D. A, B and C

5. The article (文章) tells us ______.

A. how to learn English well

B. how to swim

C. how to play football

D. how to go boating

下列关于CT图像噪声的描述中，错误的一项是（）。

A.管电流大、管电压高时，噪声水平低

B.重建算法：从高平滑到高分辨的一系列算法，其噪声水平是由低到高

C.扫描层厚：层厚越大，其噪声水平越高

D.患者体围：体积越大，相对带来的噪声也越大

E.不同的图像显示方式，其噪声水平也不一样

当一国处于经济高涨并有国际收支逆差时，应采用松的财政政策和紧的货币政策来加以调节。

我国公安机关的专政职能是专门用以对付敌对势力、敌对分子和严重刑事犯罪分子的。（）