问题 问答题 简答题

碱金属对玻璃粘度有什么影响?

答案

参考答案:

碱金属氧化物降低玻璃粘度;碱土金属对玻璃粘度的作用较为复杂,一方面类似与碱金属能使大型的四面体群解聚,引起粘度减少,另一方面这些阳离子电价较高,离子半径又不答,故键力较碱金属离子大,有可能夺取四面体群的阳离子与自己周围,使粘度增大。

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     On a typical hot August day in Xianyou County, Fujian Province, Zeng Demei, a retired worker in

his seventies, hurries down a busy street.In his hand is a black leather bag.Zeng opens his bag, taking

out two forms.  1  .

     Each of the forms contains detailed information of a student.On his arrival two hours later a woman

greets him and leads him to her office where another man is waiting.They are the two village officials.

They inspect the forms handed to them by Zeng and immediately recognize the girls.  2  . "It's a pity but

it doesn't matter."says Zeng, who wastes no time in deciding to look for the remaining child, Su Qiuju.

     After half an hour, they stop outside a small house made of mud brick.A middleaged man and a girl

in a faded pink dress greet them.Su Qiuju is eight years old.She was forced to drop out of school after

both her parents died.She is now living with her uncle who cannot afford his own children's education.

However, the year of education Su Qiuju did complete was a successful one._3_.

     When they are about to leave, Zeng says, "I must find a supporter for this girl to sponsor her

education."Zeng has made it his retirement task to help children complete their schooling.Back in 1999,

Zeng took part in a campaign started by the local women's organization to help students from poor

families. __4 _.

      His task had begun and since then he has spent his time persuading his friends and neighbors and

others to donate money."To me, children's education is the most important. __5 _. I have to find

sufficient funding before the school opens in September."

     When asked how long he will keep up his vital work as the community's guardian angel, he has a

simple reply."Not until my eyes can't see, and my feet can't move."

A. They were having problems with their schoolwork

B. These are for the two girls he's going to visit this morning

C. They live in a small village not very far, though only one of the girls is still living at home

D. She displayed a talent for handwriting, writing her threecharacter name neatly and beautifully

E. The thought of students dropping out of school bothers me so much that I can't get to sleep at night

F. Of course, some people question why I would want to give up my retirement to go to so much trouble

G. He was so overcome by the tough situation of many poor children that he donated all his money to help out a girl