发现电池电解液面过低，应及时添加（）。

If you see a group of people dancing and singing on the street or in the railway station, you don’t need to feel surprised. They are flash mobbers (快闪族). Who are they? Are they mobs(犯罪团伙)? Don’t feel afraid hearing their name. In fact, like a mob, they are a large group of people, but they have a good purpose. They usually get together in a place, do some simple actions, and then quickly disappear.

Flash mob is now becoming more and more popular. People use it to do many things. For example, in 2009, Michael Jackson’s fans took part in a flash mob to remember him. Hundreds of his fans organized through Internet and got together outside the railway station in Liverpool. They were singing and dancing Michael’s famous song “Beat It” together. And in another example, some people took part in a flash mob to tell more people not to use negative words (消极语言).

Flash mobs give different people a chance to come together to create a good memory.

小题1:Where may you see a flash mob?

A．In schools.

B．In villages.

C．In the railway stations.

D．On the playground.小题2:In 2009, hundreds of people took part in a flash mob in Liverpool railway station to ________

A．to show themselves

B．to remember Michael Jackson

C．tell people not to use negative words

D．to make a film小题3:Which of the following ideas about flash mobbers is NOT right?

A．They are usually a large group of people.

B．They usually do simple actions like singing and dancing.

C．They usually get together for a good purpose.

D．After simple actions they usually go away slowly.

一个初动能为E_k的带电粒子，以速率V垂直于场强方向射入平行板电容器两板间的匀强电场中，飞出时的动能为飞入时的动能的2倍，如果使该带电粒子以速率3V射入，则它飞出电场时的动能为（   ）

A．3E_k

B．9E_k

C．

D．

水利水电工程中永久性建筑物的级别，应根据()确定。

A、工程的等别

B、失事造成的后果

C、作用

D、使用年限

E、重要性

按照零件轮廓编程，在选用不同直径铣刀时，相应的偏移补偿量可以使用（）指令。

A.G02、G03

B.G17、G18

C.G39、G40

D.G41、G42

产业型企业集团在选择成员企业时，主要依据母公司战略定位、产业布局等因素。