问题 单项选择题 A1/A2型题

测定汞时,对253.7nm波长有吸收能力的是()

A.一价的汞离子

B.二价的汞离子

C.汞分子

D.汞原子

E.汞化合物

答案

参考答案:D

解析:汞蒸气对波长253.7nm的紫外光具有特征吸收。实验环境中苯、甲苯、氨水、丙酮、氮氧化物对波长253.7nm有吸收,应避免引起干扰。

阅读理解

阅读理解。

     Is human blood all the same? "Yes." You may say. "It's all red."

     Well, it's not as simple as you might think.

     Blood is made up of different parts, such as red blood cells (红血球), white blood cells and platelets (血小板).

     Two chemical molecules (分子) on the red blood cells make people's blood different. Scientists mark one

molecule "A" and the other molecule "B". According to which and how many molecules are on the red cell,

scientists divide blood into four types: A, B, AB and O.

     Your blood type will stay the same all your life.

     Scientists have been wondering if there are some links (联系) between people's blood types and their

personalities, but they are not certain.

     But some say that people with the same blood type may have things in common.

     What's your blood type? Do you have family members or friends who are of the same type as you?

Read the following. 

     People with Type A: They look peaceful from the outside. But they ask too much of themselves that

they may be very nervous inside. They get happy or sad easily. Sometimes they are shy but always very

careful. They can easily win people's trust.

     People with Type B: They have strong minds. Once they start a task, they don't give up easily. They'll

try their best to finish it and do it well. Type B people always try to make themselves different from others.

They want to do things in their own way.

     People with Type AB: They are maybe the strangest among all blood types. They can be both open and

shy, noisy and quiet at the same time! They are responsible and always ready to help others.

     People with Type O: They are open and good at making friends. They always start tasks but don't always

finish them. They have lots of new ideas and love to be the centre of attention. They always strongly believe

in themselves.

1. The blood types are decided by the kind and amount of molecules _______.

2. Scientists are _______ about the relations between blood and personalities.

3. If you are with Type B, you might _______.

4. If a person is both open and shy, noisy and quiet at the same time, he or she might be with _______ blood.

5. The best title of the passage is _______ and Personalities.

单项选择题 A型题