Many people are aware of the beauty of a solar eclipse (日食), but are surprised to learn that lunar eclipses are often just as impressive. While total solar eclipse lasts only for a few minutes and can be seen only in a small area of a few kilometers, total lunar eclipse can last for several hours and can be seen over much of the planet. In fact, the beauty and stability of lunar eclipses make them a favorite of both amateur and professional photographers.

    Lunar eclipses generally occur two or three times a year, and are possible only when the Moon is full. When we see the Moon, we are actually seeing sunlight reflected off the surface of the Moon When the Earth is positioned in between the Moon and the Sun, however, the Earth's shadow falls on the Moon, and a lunar eclipse occurs.

     The type of lunar eclipse - total, partial, or penumbral (半影) - that occurs depends both on how much of the Moon passes through the Earth's shadow and through which part of the shadow it passes. A penumbral eclipse occurs when the Moon passes through the Earth's outer shadow. This type of eclipse is brief and frequently goes unobserved by all but astronomers. By contrast, total and partial eclipses occur when all or part, respectively, of the Moon passes through the umbra（本影） shadow of the Earth. These eclipses are quite easy to see and are widely observed.

     Unlike solar eclipses, lunar eclipses are safe to watch. Solar radiation that occurs during an eclipse of the Sun can cause a form of burns of one's eyes known as eclipse blindness. In fact, the only way to safely view a solar eclipse is by using specially designed equipment. However, since the Moon's light is reflected sunlight, it is completely safe to watch a lunar eclipse without any special equipment, although a pair of binoculars can certainly help the viewer appreciate the beauty of this phenomenon

1.The underlined word "stability " most probably means_______.

A. strength      B. position              C. steadiness           D. visibility

2.According to the passage, a partial lunar eclipse occurs________.

A. when the Moon passes between the Sun and the Earth

B. when all of the Moon passes through the Earth's umbra shadow

C. when only a part of the Moon passes through the Earth's outer shadow

D. when only a part of the Moon passes through the Earth's umbra shadow

3.The passage implies that penumbral eclipses are________.

A. longer-lasting than most solar eclipses

B. more common than partial or full lunar eclipse

C. the result of the shadow cast by the Moon onto the Earth

D. more difficult to observe than other types of lunar eclipse

4.According to the passage, it is safe to watch a lunar eclipse, unlike a solar eclipse, because ________.

A. moonlight is less strong than sunlight

B. a lunar eclipse is briefer than a solar eclipse

C. a lunar eclipse lasts much longer than a solar eclipse

D. special equipment can be employed to view a lunar eclipse

Nuclear radiation （核辐射）has a certain mystery, partly because it cannot be detected （探测）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 or sense them without a radio receiver. Similarly, we can’t sense radioactivity 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 at once by killing plenty of cells in important organs(器官). 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 serious. This is the case when only a few cells are hit, and when they are killed at once. 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 an unusual 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 knowledge of the person at the time that damage has occurred. A person can be irradiated(放射治疗) and feel fine, then die of cancer five, ten, or twenty years later as a result. A child can be born weak or easy to get serious illness as a result of radiation absorbed by its grandparents.
【小题1】According to the passage, the danger of nuclear power lies in       .

Nuclear radiation（核辐射）has a certain mystery, partly because it cannot be detected（探测） 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 but we can’t detect them or sense them without a radio receiver. Similarly, we can’t sense radioactivity 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 important organs. 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 serious. This is the case when only a few cells are hit, and when 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 an unusual 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 knowledge of the person at the time that damage has occurred. A person can be irradiated（放射治疗）and feel fine, then die of cancer five, ten, or twenty years later as a result. A child can be born weak or easy to get serious illness as a result of radiation absorbed by its grandparents.
【小题1】According to the passage, the danger of nuclear power lies in __________.

Nuclear radiation （核辐射）has a certain mystery, partly because it cannot be detected （探测）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 or sense them without a radio receiver. Similarly, we can’t sense radioactivity 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 at once by killing plenty of cells in important organs(器官). 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 serious. This is the case when only a few cells are hit, and when they are killed at once. 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 an unusual 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 knowledge of the person at the time that damage has occurred. A person can be irradiated(放射治疗) and feel fine, then die of cancer five, ten, or twenty years later as a result. A child can be born weak or easy to get serious illness as a result of radiation absorbed by its grandparents.

1.According to the passage, the danger of nuclear power lies in       .

2.Radiation can lead to serious trouble even at the lowest level        .   

3.What does the author want to tell us?

Nuclear radiation（核辐射）has a certain mystery, partly because it cannot be detected（探测） 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 but we can’t detect them or sense them without a radio receiver. Similarly, we can’t sense radioactivity 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 important organs. 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 serious. This is the case when only a few cells are hit, and when 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 an unusual 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 knowledge of the person at the time that damage has occurred. A person can be irradiated（放射治疗）and feel fine, then die of cancer five, ten, or twenty years later as a result. A child can be born weak or easy to get serious illness as a result of radiation absorbed by its grandparents.

1.According to the passage, the danger of nuclear power lies in __________.

2.Radiation can lead to serious trouble even at the lowest level __________.

3.Radiation can hurt us so much that it can ___________.

4.Which of the following can be best inferred from the passage?

5.What would be the best title of the text?