[简答题]The energy contained in rock within the earth’s crust (地壳) represents a nearly unlimited energy source, but until recently commercial retrieval has been limited to underground hot water and/or steam recovery systems. These systems have been developed in areas of recent volcanic activity, where high rates of heat flow cause visible eruption of water in the form of geysers and hot springs. In other areas, however, hot rock also exists near the surface but there is insufficient water present to produce eruptive phenomena. Thus a potential hot dry rock (HDR) reservoir exists whenever the amount of spontaneously produced geothermal fluid has been judged inadequate for existing commercial systems.
As a result of the recent energy crisis, new concepts for creating HDE recovery systems—which involve drilling holes and connecting them to artificial reservoirs placed deep within the crust—are being developed. (46) In all attempts to retrieve energy from HED’s reservoir artificia

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The energy contained in rock within the earth’s crust represents a nearly unlimited energy source, but until recently commercial retrieval has been limited to underground hot water and/ or steam recovery systems. These systems have been developed in areas of recent volcanic activity, where high rates of heat flow cause visible eruption of water in the form of geysers and hot springs. In other areas, however, hot rock also exists near tile surface but there is insufficient water present to produce eruptive phenomena. Thus a potential hot dry rock (HDR) reservoir exists whenever the amount of spontaneously produced geothermal fluid has been judged inadequate for existing commercial systems.
As a result of the recent energy crisis, new concepts for creating HDR recovery systems— which involve drilling holes and connecting them to artificial reservoirs placed deep within the crust—are being developed. In all atte
A. alert readers to the existence of HDR’s as an available energy source
B. document the challenges that have been surmounted in the effort to recover energy from HDR’s
C. warn the users of coal and oil that HDR’s are not an economically feasible alternative
D. encourage the use of new techniques for the recovery of energy from underground hot water and steam

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Sedimentary rock hardens within the earth’s crust as layers of matter accumulate and the pressure of the layers above converts the layers below into rock. One particular layer of sedimentary rock that contains an unusual amount of the element iridium has been presented as support for a theory that a meteorite collided with the earth some sixty million years ago. Meteorites are rich in iridium compared to the earth’s crust, and geologists theorize that a meteorite’s collision with the earth raised a huge cloud of iridium-laden dust. The dust, they say, eventually settled to earth where it combined with other matter, and as new layers accumulated above it, it formed a layer of iridium-rich rock.
Which one of the following, if true, would counter the claim that the iridium-rich layer described in the passage is evidence for the meteorite collision theory（）

A. The huge dust cloud described in the passage would have blocked the transmission of sunlight and lowered the earth’s temperature
B. A layer of sedimentary rock takes millions of years to harden
C. Layers of sedimentary rock are used to determine the dates of prehistoric events whether or not they contain iridium
D. Sixty million years ago there was a surge in volcanic activity in which the matter spewed from the volcanoes formed huge iridium-rich dust clouds
E. The iridium deposit occurred at about the same time that many animal species became extinct and some scientists have theorized that mass dinosaur extinctions were caused by a meteorite collision

[简答题] The earth we live is a ball of very hot rock. It is good for us that the outside shell is cold. If it were not, no one could live here. What if our earth were only as big as an egg Then the outside part would be as deep as the egg’’s shell. The earth’’s shell has cracks in it in some places. In New Zealand, this shell seems to have more cracks than in other places on the earth. There are spots where the ground is so hot that it burns the bottom of your shoes. In some places, hot water shoots into the air from time to time. At other points, you can see steam coming up from pools of hot water. The people who live in North Island, New Zealand, make use of the heat that comes from inside the earth. Some of them cook in the hot pools. They put food into a basket and place it in the water. Washing clothes is done in much the same way. Many people bring the hot water from below the earth into their houses, They do this by putting a pipe a hundred feet or more into the ground.

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Escaping from the Earth
The Earth has a force that pulls things toward itself. We call this force gravity(地心引力). This is something we live with all the time, and we take it for granted and hardly ever think about it. But it is a most important factor in rocket operation and must be overcome if we are to get anywhere in space, or off the ground at all.
Take the throwing of a hall as an example. The harder the ball is thrown, the faster and higher it will go. What is the secret Its speed. If we could throw the ball hard enough it would go up and up forever and never come down. The speed at which it would have to be thrown to do this is known as escape speed. Of course, we cannot throw a ball hard enough because the speed required to escape completely from the Earth’s gravity is seven miles per second, or over twenty-five thousand miles per hour.
Once escape speed has been reached by a spacecraft(宇宙飞船), no further power is needed. A rocket aimed
A. Few spacecrafts complete their flight operations.
B. The Earth’s gravity cannot be overcome.
C. No future power is needed after the escape speed is reached.
D. "Free fall" takes the place of the Earth’s gravity pull.