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We experience different forms of the Sun’s energy every day. We can see its light and feel its warmth. The Sun is the major source of energy for our planet. It causes the evaporation （蒸发） of water from the oceans and lakes. Sunlight also provides the energy used by green plants to make their own food. These green plants then provide food for all organisms （生物） on the Earth.
Much of the energy that comes from the Sun never reaches the Earth’s surface. It is either reflected or absorbed by the gases in the upper atmosphere. Of the energy that reaches the lower atmosphere, 30% is reflected by clouds or the Earth’s surface. The remaining 70% warms the surface of 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 surface back to the Earth. These gases act like the glass of a greenhouse in that they allow energy from the Sun to enter but prevent energy from leaving. They are therefore called greenhouse gases.
When sunlight strikes an object, some of the energy is absorbed and some is reflected. The amount reflected depends on the surface. For example, you’ve probably noticed how bright snow is when sunlight falls on it. Snow reflects most of the energy from the Sun, so it contributes to the low temperatures of winter. Dark-coloured surfaces, such as dark soil or forest, absorb more energy and help warm the surrounding air.
1. According to the passage, the root cause for weather changes on the Earth is ______.
A. the atmosphere surrounding the Earth
B. water from oceans and lakes
C. energy from the Sun
D. greenhouse gases in the sky
2. Only a small part of the Sun’s energy reaches the Earth’s surface because most of it is ______.
A. absorbed by the clouds in the lower atmosphere
B. reflected by the gases in the upper atmosphere
C. lost in the upper and lower atmosphere
D. used to evaporate water from the oceans and lakes
3. We learn from the passage that ______.
A. all living things on the Earth depend on the Sun for their food
B. a forest looks dark in winter because it absorbs solar energy
C. only 0.023% of the energy from the Sun is made use of on the Earth
D. greenhouse gases allow heat energy to escape from the Earth’s surface
warmth n . 温暖
major source 主要来源
reflect v . 反射（光、音、声），映出（形象）
upper atmosphere 高层大气，高空大气
water cycle 水循环
greenhouse gases 温室气体
contribute to 有助于……，促成
dark-coloured adj . 深色的
1. The remaining 70% warms the surface of the planet, causes water to evaporate, and provides energy for the water cycle and weather.
remaining表示“剩余的”。本句结构比较清晰，三个谓语动词分别是warm、cause和provide。water cycle的意思是“水循环”。
（参考译文） 剩余70%的能量使地球表面变得温暖，使水分能够蒸发，并为水循环和天气变化提供能量。
2. Many gases found in the atmosphere actually reflect heat energy escaping from the Earth’s surface back to the Earth.
found此处引导后置定语，表示“在大气中发现（存在）的”，reflect...back to... 表示“将……反射回……”，escaping from the Earth’s surface是现在分词引导的定语短语，修饰heat energy。
（参考译文） 在大气中存在的许多气体实际上将从地球表面逃逸出来的热能反射回地球。