下列化合物中，只有在水溶液中才能导电的电解质是（ ） A．BaSO4 B．碳酸钠

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 if you want to be a football

player, you must play football.

     So, you see. You can learn English only by using it. You must listen to your teacher in class.

     You must read your lessons every day. You must speak English to your classmates and you must

write something sometimes. Then one day, you may find your English very good.

1.You know a lot about English but maybe          .

A.you can speak

B.you can study it 

C.you can't study it

D.you can't use it

2.You must get into the river          .

A.to catch a fish

B.to learn how to swim

C.to go boating 

D.to play with water

3.If you want to be a football player, please          .

A.buy a good football 

B.play football

C.watch others play football

D.put your football away

4.If you want to study English well, you must often           .

A.speak English

B.write in English

C.listen to English

D.do all of A.B.C

5.From the passage we know "         ".

A.You know an apple good or not if you eat it

B.You can't do anything if you don't know how to do it

C.You must speak English before you know how to use it

D.Swimming is a good example for you to learn English well

铁路货物运输是使用铁路列车运送货物的一种运输方式，主要承担______。

A．长距离、大宗货物运输
B．长距离、小宗货物运输
C．短距离、大宗货物运输
D．短距离、小宗货物运输

物资消耗管理中，钢筋损耗率≯（）。

A.0.5%

B.1.5%

C.2.0%

D.2.5%

木屋架在范围作用下，其（）往往随时间变化。

A.刚度

B.强度

C.挠度