问题 单项选择题

抗原抗体反应中,前带现象因何原因引起

A.抗原过剩

B.抗体过剩

C.pH值的变化

D.温度的变化

E.离子强度的变化

答案

参考答案:B

解析:沉淀反应时在等价带前后,由于抗体或抗原过量,上清液中可测出游离的抗体或抗原,形成的沉淀物少,这种现象称为带现象,抗体过量称为前带现象,抗原过量称为后带现象。

完形填空

Jim, a successful businessman, told the experience of his childhood.

When he was 12, his parents       . He was alone and didn’t get on well with others. People always laughed        him. No one showed kindness (友善) to him. His only friend was a dog named Tige.

One day as he walked down the street, a young lady was walking in front of him. Suddenly one of her bags dropped from her arms. As she stopped       , she dropped other bags. He came to help her.“Thank you, dear! You are a nice little boy!”She said kindly, smiling.

A special feeling came to him. These were        kind words he had ever heard. He watched her        she went far away, and he whistled(吹口哨)to his dog and went directly to the river nearby.

“Thank you, dear! You are a nice little boy!”he repeated the woman’s words. Then in a low        he said to his dog,“You are a nice little dog!”Tige raised        ears as if(似乎)it understood.

“Uh! Even a dog likes it!”he said,“Well, Tige, I won’t say unkind words to you any more.”Tige waved its tail happily.

The boy thought and thought. Finally he looked at himself in the river. He saw        but a dirty boy. He washed his face       . Again he looked. He saw a clean nice boy. He was amazed (震惊). From then on, he had a new life.

After telling this, the businessman stopped for a while, and then he said,“Ladies and gentlemen, this is the place where that kind woman planted in me the first seed (种子) of kindness. All of us should learn about kindness.        a great power it has!” If you show kindness to others, you will be an able man.

小题1:A.dead              B. die               C.died

小题2:A.at                B.to              C.of

小题3:A.picking it up        B to pick it up      C.to pick up it

小题4:A.the first            B.first              C. the first time

小题5:A.until                B.before          C.when

小题6:A.sound             B.noise           C..voice

小题7:A.it                B.it’s             C. its

小题8:A.something            B.nothing         C. somebody

小题9:A.carefully            B.careful         C.careless

小题10:A.What             B.How            C.It

单项选择题