合成水冷器结垢的主要原因是（）A、循环水碱度过高； B、循环水量少； C、循环水PH

Rayleigh的设计原理是，散射光的强度与复合物的量成________________，与散射夹角成______________，与波长成________________。

把下面画线部分的句子翻译成中文。

     You probably think you will never be a top student. In fact, you can become a better student if you want

to. You maybe say, 1"It takes me lots of time to study, but I don't still make progess." But if you can use your

time well, you may improve your study without much work. There are a few ways here to help you with your

study. 

     2 Plan your time carefully. You should make a list of things that you have to do during a week. First, you

should write down the time for eating, sleeping, dressing, etc. Then you should use the time that you can study.

3 Of course, studying shouldn't take all of your time. Don't forget to leave enough time for hobbies yourself.

     Find a good place to study. Keep this place, which may be a desk or just a corner of your room. No games,

radio, or television! When you sit down to work, think only about the subject!

     Make good use of your time in class. 4 Listen to what the teacher says carefully. Careful listening in class

means less work later. You also need to take notes in class, because it can make it easier for you to learn well.

     5 Can you give any other ways to study?

1._____________________________________________________

2._____________________________________________________

3._____________________________________________________

4._____________________________________________________

5._____________________________________________________

消防系统的布置要点包括室内顶棚设计与烟感报警器的布置；室内顶棚设计与喷淋头、水幕的布置设备；室内（）与消火栓箱布置的关系；起装饰部件作用的轻便灭火器的选用与布置。

A.绿化设计

B.墙面设计

C.洁具设计

D.造型设计

某过程特性的真实（总体）均值150和真实（总体）标准差20，从这个过程中抽样25项。样品的标准差是：（）

A.0.2

B.0.8

C.4.0

D.5.0

热塑性和热固性聚合物流变行为的比较