[填空题]Two-thirds of the earth’s surface (be) ______ covered with water.

[填空题]S3. If the temperature at the earth’s surface is 20F, the temperature in a coal mine 500 feet below the surface would be _____________________.

[填空题]Earth’s surface releases some of the heat from the Sun as______.

[单项选择]It has been estimated that the earth’s surface temperature has increased （　） one quarter to three quarters of a degree since 1805.
A. to
B. by
C. at
D. with

[单项选择]Most of Earth’s surface is ocean. The ocean floor is inaccessible for extensive research without equipment of greater technological sophistication than is currently available. It must therefore be true that scientists know less about the ocean floor environment than about almost any other environment on Earth.
Which of the following, if true, provides the most support for the conclusion
A. Many mountain ranges lie entirely beneath the ocean surface, yet new underwater surveying equipment has produced three-dimensional charts of them that are as accurate as those available for mountain ranges on land.
B. Strong water currents circulate on the ocean floor, but the general pattern of their movement is not so well understood as is the pattern of air currents that circulate over land.
C. In contrast to most land environments, temperature conditions at the ocean floor are generally stable and uniform, since sunlight does not penetrate far below the ocean surface.
D. Very few people have seen detailed maps of extended regions of the ocean floor, even though such maps are available in almost all large libraries.
E. (E) Animals living on the ocean floor must be able to withstand water pressure that is far greater than the atmospheric pressure with which land animals live.

[单项选择]A. The weight of an object on the Earth’s surface.
B. The power of attraction between two objects.
C. The natural beauty of an object in space.
D. The attraction of ancient objects and relics.

[填空题]Two-thirds of the earth’s surface (be)（）covered with water.

[单项选择]In Earth’’s infancy, its surface was warm enough for life ____ the young Sun was fainter than it is today.
A. in spite of
B. whether
C. neither of which
D. even though

[填空题]The average surface temperature of Earth keeps around 15℃.

[单项选择]

All the useful energy at the surface of the earth comes from the activity of the sun. The sun heats and feeds creatures and mankind. Each year it provides men with two hundred million tons of grain and nearly ten million tons of wood, coal, oil, natural gas, and all other fuels are stored energy from the sun. (80) Some was collected by this season’ s plants as carbon compounds. Some was stored by plants and trees ages ago. Even waterpower derives from the sun. Water turned into vapor by the sun fails as rain. It courses down the mountains and is converted to electric power. Light transmits only the energy that comes from the sun’ s outer layer, and much of this energy that is directed towards the earth never arrives. About nine tenths of it is absorbed by the atmosphere of the earth. In fact, the earth itself gets only one half millionth of the sun’s entire output of radiant energy.

The sun is the source of all of the following EXCEPT（）
A. gasoline
B. natural gas
C. atomic power
D. animal fat

[单项选择]All useful energy at the surface of the earth comes from the activity of the sun. The sun heats and feeds mankind. Each year it provides men with two hundred million tons of grain and nearly ten million tons of wood.
Coal, oil, natural gas, and all other fuels are stored-up energy from the sun. Some was collected by this season’s plants as carbon compounds. Some was stored by plants and trees ages ago.
Even waterpower derives from the sun. Water turned into vapor by the sun falls as rain. It courses down the mountains and is converted to electric power.
Light transmits only the energy that comes from the sun’s outer layers, and much of this energy that is directed toward the earth never arrives. About nine-tenths of it is absorbed by the atmosphere of the earth. In fact, the earth itself gets only one half-billion of the sun’s entire output of radiant energy.
Radiant energy is stored as carbon compounds by ______.
A. plants
B. rain
C. rock
D. wind