除去下列物质中所含杂质的方法正确的是 物 质杂 质除杂试剂提 纯 方 法AKCl

题型:选择题

问题:

除去下列物质中所含杂质的方法正确的是

 物 质杂 质除杂试剂提 纯 方 法
AKClMnO2充分溶解、过滤、蒸发
BCO2COO2点燃
CNaClNa2CO3硝酸足量加入硝酸溶液
DAgNO3溶液Cu(NO3)2Cu粉加入少量的铜粉,过滤

考点:石灰石的利用盐的用途
题型:选择题

Read and choose. (阅读短文,根据短文意思,选择最合适的答案)  

     A man was looking for things of old times. One day he came to a village and found a blue bowl 

which looked very old. The bowl was on the ground and a cat was drinking milk from it. A farmer, 

the owner of the cat, was lying beside the bowl. The man thought the farmer didn't know the value

(价值) of the bowl.  So he said to the farmer in a soft voice,  " What a nice cat you have! Won't 

you sell it to me?"        

     "How much would you give me for it?" the farmer  opened his eyes and 

asked.                                                                                                                     

     "Twenty dollars. Would it be enough?"      

     A few minutes later, the farmer agreed. After he paid the farmer, the man said, "My cat will certainly 

feel thirsty.  May I take the bowl so that the cat can have milk?"      

     But the farmer said, "I'm sorry. I can't give it to you. Thanks to the bowl, I have already sold twenty 

cats.

1. The man liked _____.       

A. keeping old things                      

B. meeting farmers

C. traveling from village to village        

D. buying cats

2. Why did the man want to buy the cat? Because _____.            

A. it was very lovely

B. the cat cost more money than the bowl

C. he thought he could easily get the bowl if he bought the cat

D. he hadn't enough money to buy both the cat and the bowl

3. After he bought the cat, the man asked for the bowl, because he thought _____.            

A. the bowl should go with the cat

B. the bowl had a beautiful colour

C. the farmer didn't know the value of the bowl

D. the cat could not live without the bowl

4. The farmer kept the bowl so that he could _____.          

A. let another cat use it                      

B. sell more cats

C. sell more bowls                        

D. use the bowl himself

5. The farmer has already sold _____ cats.          

A. thirty                                     

B. ten

C. forty                                        

D. twenty

题型:选择题
口算
24×5=
32+94=50×6=
200×12=15×100=
题型:选择题

带电粒子穿过物质时,受原子核的电场作用而改变速度,失去动能,其中的一部分动能以电磁波的形式辐射出来,这叫()。

A.弹性散射

B.湮灭辐射

C.轫致辐射

D.康普顿散射

E.光电效应

题型:选择题

《史记》中,用来记叙诸侯事迹的是

A.世家

B.本纪

C.列传

D.书

题型:选择题

螺杆泵的保护器其保护作用是()。

A、保护电机

B、保护分离器

C、保护泵

D、保护减速器

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