问题 问答题 简答题

成品取样时钢液中加铝丝的目的和注意什么?

答案

参考答案:

必须指出,使金属脱氧时绝不可使用没有除净橡皮的铝丝,因为橡皮含硫,以免硫进入金属试样内,增高硫的含量.另外没有脱氧的沸腾金属试样含有大量气孔,会使试样难于钻孔,其次能使碳,磷特别是硫局部偏析增大.使用铝脱氧的金属试样内,偏析只存在于铸件的上部。

阅读理解

阅读理解。

     Easter Sunday is one of the most important religious (宗教) holidays. It is on the first Sunday after

the full moon or after March 21. It is celebrating for the rising of Jesus Christ from his tomb (坟墓).

Before he died, he said he would come back to life again.

     There are a lot of symbols (符号) for Easter. Of all the symbols, we see the eggs and the rabbits

most. American children believe that the Easter Rabbit brings chocolate eggs at Easter, so they carry

small baskets to look for coloured eggs. The eggs are in the grass, near the house or in the trees.

Americans hold eggs rolling on Easter Monday morning every year in front of the White House. The

most famous one is along the Fifth Avenue (大街) in New York City. Students usually have a week-long

holiday. They often go home to have an Easter dinner with their families.

1. Easter Sunday is in _____.

A. spring     

B. summer    

C. fall    

D. winter

2. How many symbols can we see on the Easter Sunday?

A. One.   

B. Two.    

C. More than two.    

D. No symbol.

3. Easter Sunday is celebrating for _____.

A. the death of Jesus Christ         

B. the harvest  

C. the birthday of Jesus Christ       

D. the rising of Jesus Christ

4. Americans hold eggs rolling _____ every year in front of the White House.

A. on Easter Sunday morning        

B. on Easter Sunday evening 

C. on Easter Monday morning       

D. on Easter Monday evening 

5. How long can students stay at home on Easter holiday?

A. Two days.   

B. Seven days.   

C. Four days.   

D. Five days.

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