问题 单项选择题 A1/A2型题

若抗原或抗体极度过剩而无沉淀形成,称为()。

A.带现象

B.等价带

C.前带

D.后带

E.比例性

答案

参考答案:A

解析:抗原抗体反应的特点之一是比例性。只有当抗原抗体的分子比例合适时,反应最充分,形成的沉淀物最多,称为等价带。抗原或抗体极度过剩则不形成沉淀,成为带现象。抗体过量时称前带;抗原过量时称后带。

阅读理解

阅读理解

     Mrs. White was very fat. She weighed (重) 100 kilos, so she went to see a doctor. The doctor said,

"You need a diet (节食), Mrs. White, and I have a good way here." He gave Mrs. White a small book

and said, "Read this carefully and eat the things on page 11 every day. Then come back and see me in

two weeks."

     Mrs. White came again two weeks later, but she wasn't thinner. She was fatter than before. The

doctor was surprised and asked, "Are you eating the things on page 11 of the small book?" "Yes,

doctor." she answered.

     The next day the doctor visited Mrs. White during her dinner. He was very surprised at what he

saw. "Mrs. White,"  he said, "why are you eating potatoes and bread? They aren't in your diet."

"Doctor," Mrs. White answered, "I follow my diet at lunchtime. But this is my dinner."

1.Why did Mrs. White go to see a doctor?

A.Because she had a bad cold.

B.Because she felt terrible.

C.Because the doctor was her friend.

D.Because she wanted to be thinner.

2.The doctor asked her to _______.

A.eat more food

B.eat less food

C.eat nothing

D.eat healthy food

3.After two weeks,Mrs. White became _______.

A.fatter

B.thinner

C.healthier

D.stronger

4.Why was the doctor surprised when he visited Mrs. White during her dinner?

A.Because she eat nothing.

B.Because she was eating meat.

C.Because she was eating potatoes and bread.

D.Because she wasn't in.

5.What's the meaning of "I follow my diet at lunchtime. But this is my dinner."?

A.She always followed the diet.

B.She didn't follow the diet.

C.She didn't like the diet.

D.She only followed the diet at lunchtime, and she didn't follow the diet at dinner.

单项选择题