题目内容
（请给出正确答案）
[主观题]
______ is a surface that forms a common area or boundary similar in many respects to grain boundarie
s between any two constituents in a monolithic material.
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发布时间：2022-01-06
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We experience different forms of the sun' s energy every day．The sun is the major source ofenergy for our planet．It causes the evaporation (蒸发) of water from the oceans and lakes．Sun-light also provides the energy used by green plants to make their own food．
Much of the energy that comes from the sun never reaches the earth' s surface．It is either re-fleeted or absorbed by the gases in the upper atmosphere．Of the energy that reaches the lower at-mosphere, 30% is reflected by clouds or the earth' s surface．The remaining 70% warms the surfaceof the planet, causes water to evaporate, and provides energy for the water cycle and weather．
Only a tiny part, approximately 0．023%, is actually used by green plants to produce food．
Many gases found in the atmosphere actually reflect heat energy escaping from the earth' s sur-face back to the earth．These gases act like the glass of a greenhouse in that they allow energy fromthe sun to enter but prevent energy form. leaving．They are therefore called greenhouse gases．
When sunlight strikes an object, some of the energy is absorbed and some is reflected．Theamount reflected depends on the surface．Dark-colored surfaces, such as dark soil or forest, absorbmore energy．
According to the passage， the root cause for weather changes on the earth is __________． 查看材料
A.the atmosphere surrounding the earth
B.water from oceans and lakes
C.energy from the sun
D.greenhouse gases in the sky
