Earth is a rocky planet liquid water, which is necessary for life, can exist. A. as B. which C. where D. when 题目和参考答案——青夏教育精英家教网—

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Earth is a rocky planet _______ liquid water, which is necessary for life, can exist.

A. as B. which C. where D. when

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Geologists have been studying volcanoes for a long time.Though they have learned a great deal,they still have not discovered the cause of volcanic action.They know that the inside of the earth is very hot,but they are not sure exactly what causes the great heat.Some geologists have thought that the heat is caused by the great pressure of the earth’s outer layers.Or the heat may be left from the time when the earth was formed.During the last sixty years scientists have learned about radium,uranium,thorium,and other radioactive elements.Many scientists now believe that much of the heat inside the earth is produced by radioactive elements.

Whatever the cause of the heat may be,we do know that the earth gets hotter the farther down we dig.In deep mines and oil wells the temperatures rise about 1°F for every 50 feet.At this rate of the temperature 40 miles below the earth’s surface should be over 4 000°.This is much hotter than necessary to melt rock.However,the pressure of the rock above keeps most materials from melting at their usual melting points.Geologists believe that the rock deep in the earth may be plastic,or puttylike（油灰状的）.In other words,the rock yields slowly to pressure but is not liquid.But if some change in the earth’s crust releases the pressure,the rock melts.Then the hot,liquid rock can move up toward the surface.

1.The cause for the great heat inside of the earth is______.

A.great pressure of the earth’s outer layers

B.the heat left from the time when the earth was formed

C.radioactive elements giving out heat

D.not sure

2.According to the passage,______ prevents most rock from melting at its usual melting points.

A.the pressure of the rock itself

B.the pressure of the rock above

C.the pressure of the earth’s outer layers

D.the heat given out by some radioactive elements

3.According to the passage,which of the following is NOT true?

A.The farther down,the hotter the earth gets.

B.The rock deep in the earth is liquid.

C.When the pressure releases from the earth’s crust,the rock melts.

D.Rock would be melted at 4 000°.

单句改错（共5小题，共5分）
【小题1】Each boy and each girl were given a chance to compete in the game.
【小题2】Mary mustn’t be in the library, for she went to the hospital with her mother just now.
【小题3】Great changes have been taken place in my hometown in the past ten years.
【小题4】Seeing from the spaceship, the earth is a huge water globe.
【小题5】It’s very cold outside. You’d better to put on more clothes.

Seen from (the) outer space, the earth is ________ a blue ball

A．anything but

B．nothing more than

C．not more than

D．none other than

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 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 _______________.

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

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