在生物传种接代过程中，能够使染色体保持一定的稳定性和连续性的重要生理过程是： ①

可接受B型血的包括下列哪些（）

A.A型血患者

B.B型血患者

C.O型血患者

D.O型血或B型血患者

E.O型血或A型血患者

写出一个解为2的一元一次方程是﹙    ﹚

1mol白磷转化为红磷时放出18.39kJ热量，已知：P₄(白磷，s)+5O₂(g)＝2P₂O₅(s) 

ΔH=－a kJ/mol(a>0)；4P(红磷，s)+5O₂(g)=2P₂O₅(s)  ΔH=－bkJ/mol(b>0)，则a和b 的 关系是（   ）

A．a > b

B．a = b

C．a < b

D．无法确定

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.

关于美国行政法，以下说法不正确的是（）

A、以洲际贸易委员会的成立为产生标志；

B、最大特色体现为其行政程序法；

C、行政裁决与法院审判性质相同；

D、不存在单独的行政法院；