【单选题】{{B}}Text 4{{/B}}
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.
B．meaningful
C．fatal
D．harmful
网考网参考答案：D
网考网解析：
harmful意为“有害的”，题中的significant意为“重大的；有意义的”。据第三段第四句：“如果辐射没有辐射到重要部位，那么损害就不大”，得知not be significant“没有意义”，即“无大碍”，也就足“无害”，因此significant的意思为harmful。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>
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