问题 填空题

我们通常按组成或性质对物质进行分类。下列每组物质都有一种物质与其他物质所属类别不同,试分析每组中物质的组成规律,将这种不同于其他物质的物质找出来,将其填在题后的横线上。

(1) NaCl、KCl、NaClO、BaCl2________

(2) HClO3、KClO3、Cl2、NaClO3________

(3) H3PO4、H4SiO4、HCl、H2SO4

(4)铜、金、磷、钠________

(5)空气、NH3、HCl、CuSO4·5H2O________

答案

(l)NaClO

(2)Cl2

(3)HCl

(4)磷

(5)空气

单项选择题

Nuclear power’s danger to health, safety, and even life itself can be summed up in one word: radiation.

Nuclear radiation has a certain mystery about it, partly because it cannot be detected by human senses. It can’t be seen or heard, or touched or tasted, even though it may be all around us. There are other things like that. For example, radio waves are all around us but we can’t detect them, sense them, without a radio receiver. Similarly, we can’t sense radio activity without a radiation detector. But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things.

At very high levels, radiation can kill an animal or human being outright by killing masses of cells in vital organs. But even the lowest levels can do serious damage. There is no level of radiation that is completely safe. If the radiation does not hit anything important, the damage may not be significant. This is the case when only a few cells are hit. And if they are killed outright, your body will replace the dead cells with healthy ones. But if the few cells are only damaged, and if they reproduce themselves, you may be in trouble. They reproduce themselves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years.

This is another reason for some of the mystery about nuclear radiation. Serious damage can be done without the victim being aware at the time that damage has occurred. A person can he irradiated and feel fine, then die of cancer five, ten, or twenty years later as a result. Or a child can be born weak or liable to serious illness as a result of radiation absorbed by its grandparents.

Radiation can hurt us. We must know the truth.

Which of the following can be best inferred from the passage()

A. The importance of protection from radiation cannot be over-emphasized

B. The mystery about radiation remains unsolved

C. Cancer is mainly caused by radiation

D. Radiation can hurt those who are not aware of its danger

选择题