| The exploitation of the power in the
Sun’s rays is a form of alternative energy now showing new commercial
promise. In the US, manufacturers have made important{{U}} (26) {{/U}}in the development of the technology to bring down the cost of solar conversion systems{{U}} (27) {{/U}}improving their reliability. The direct conversion of solar{{U}} (28) {{/U}}electrical energy, using photovoltaic cells{{U}} (29) {{/U}}distinct advantages as an alternative energy option. {{U}} (30) {{/U}}other forms of renewable energy, photovoltaic is based on modular solid state devices which can be mass{{U}} (31) {{/U}}at a relatively low cost. Here wafers of silicon—not dissimilar{{U}} (32) {{/U}}ones which are turned into silicon chips—{{U}} (33) {{/U}}an electric current when light falls upon them. When built into p A. while B. if C. of D. for [填空题]The ozone layer (must be protected) because (it) shields the Earth (from) excessive ultra-vilolet (radiations).
A. must protected B. it C. from D. radiations
[填空题]Some of the Sun’s radiation that is absorbed by the Earth’s surface becomes heat energy in the form of ______.
[单项选择]We experience different forms of the sun’s energy every day. 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.
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 form leaving. They are there A. the atmosphere surrounding the earth B. water from oceans and lakes C. energy from the sun D. greenhouse gases in the sky [单项选择]Without the sun's light ______ the earth's surface, no life could exist on the earth.
A. warms B. warmed C. warming D. to warm [简答题]将文件夹下JIN文件夹中的SUN.C文件复制到文件夹下的MQPA文件夹中。
我来回答: 提交
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