整流变故障跳闸后的事故处理步骤有哪些？

Try reading the following sentences as fast as you can. “ She sells seashells by the seashore. The shells she sells are surely seashells. So if she sells shells in the seashore, I’m sure she sells seashore shells.”

Not very easy, was it? What you’ve just read is called a tongue twister（绕口令）. It is an exercise made up of sounds that are hard to pronounce in order to help people pronounce words faster and more correctly. Try the next example.

“Peter Piper picked a peck of picked peppers, Did Peter Piper pick a peck of picked peppers? If Peter Piper picked a peck of picked peppers, where’s the peck of picked peppers Peter picked?”

Tongue twisters usually do not have much meaning. They are just designed to improve people’s ability（能力）to pronounce words. Although they may be very difficult, these exercises are very important to people who are trying to speak English correctly. This is because tongue twisters help people to tell the differences between similar sounds.

So if you wish to pronounce words more smoothly, you’d better try picking out some tongue twisters and practicing them.

小题1:Tongue twisters are helpful in improving ________ skills.

A．listening

B．writing

C．pronunciation

D．communication小题2:The first tongue twister is hard because _________.

A．it is very boring to read

B．it teaches us a lot of knowledge

C．we don’t know who “she” is

D．the sounds of “s” and “sh” are similar小题3:What does the “ability” mean in Paragraph 4?

A．Pronouncing words faster and more correctly.

B．Pronouncing words faster

C．Knowing the meaning of words.

D．Picking out tongue twisters smoothly.

下列哪项为等张溶液（）

A.0.85％NaCl溶液

B.10％葡萄糖溶液

C.1.9％尿素溶液

D.20％甘露醇溶液

E.0.85％葡萄糖溶液

通常电路中的能耗元件是指

A．电阻元件

B．电容元件

C．电感元件

D．电源元件

林可霉素长期用药可引起的不良反应是

A．肾功能损害
B．过敏性休克
C．再生障碍性贫血
D．永久性耳聋
E．假膜性肠炎

（）围成的曲面体称为回转体。

A.全部由曲面

B.由曲面和平面共同

C.由回转面

D.全部由平面