2. 职称英语
  3. A summary of the physical and chemical nature of life must begin, not on the

A summary of the physical and chemical nature of life must begin, not on the

游客2023-07-11  42
问题     A summary of the physical and chemical nature of life must begin, not on the Earth, but in the Sun; in fact, at the Sun’s very center. It is here that is to be found the source of the energy that the Sun constantly pours out into space as light and heat. This energy is liberated at the center of the Sun as billions upon billions of nuclei of hydrogen atoms collide with each other and fuse together to form nuclei of helium, and, in doing so, release some of the energy that is stored in the nuclei of atoms. The output of light and heat of the Sun requires that some 600 million tons of hydrogen be converts into helium in the Sun every second. This the Sun has been doing thousands of millions of years.
    The nuclear energy is released at the Sun’s center as high-energy gamma radiation, a form of electro magnetic radiation like light as radio waves, only of every much shorter wavelength. This gamma radiation is absorbed by atoms inside the Sun, to be reemitted at slightly longer wavelengths. This radiation, in its turn, is absorbed and reemitted. As the energy filters through the layers of the solar interior, it passes through the x-ray part of the spectrum, eventually becoming light. At this stage, it has reached what we call the solar surface, and can escape into space, without being absorbed further by solar atoms. A very small fraction of the Sun’s light and heat is emitted in such directions that, after passing unhindered through interplanetary space, it hits the Earth. [br] It can be inferred from the passage that the Sun’s light travels ______.
选项 A、through solid objects in space
B、in many different directions
C、more slowly than scientists previously believed
D、further in summer than in winter
答案 B
解析 根据文章最后两句，太阳的光和热被太阳原子吸收而释放在太空的一小部分光和热散发至各个方向，无阻拦地通过星际空间后，就到了地球，由此可知，太阳光是向多个方向释放、的。故B项为正确。
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