. When coal is burned in a boiler, two kinds of ash by-products are produced: a heavy bottom ash and a fine-as-powder fly ash. About 10 to 15 percent of the coal by-product is bottom ash which is used 题目和参考答案——青夏教育精英家教网—

题目内容

When coal is burned in a boiler, two kinds of ash by-products are produced: a heavy bottom ash and a fine-as-powder fly ash. About 10 to 15 percent of the coal by-product is bottom ash which is used like sand on streets and highways covered with ice, and also on highways as paving material.

It is the fly ash, however, that is receiving much attention. Once considered a waste, fly ash is now regarded as a natural resource in the United States. It can be placed in some lower places, where it is compacted（压实） and covered with soil, for the seeds of various grasses and plants to be placed in the soil to make the land productive.

Fly ash may be added to concrete (混凝土）to build roads and other kinds of buildings, taking the place of the cement(水泥) up to 20 percent. As a by-product of burned coal, fly ash requires no extra energy to be produced, while cement production requires great amounts of energy.

Besides, the technology is able to take out some useful minerals from the fly ash, which is still a very expensive process today. But the time may come when it is cheaper to take out these products from ash than to mine new supplies.

49. The bottom ash can be put on icy streets________.

A. in order to rebuild them B. in order to make them colorful

C. so that people can walk on them D. so that cars can run faster

50. The fly ash can be used to________.

A. grow various plants B. take the place of soil

C. cover productive land D. make more productive land

51. Which of the following is right?

A. To produce fly ash, some extra coal is to be burned.

B. Fly ash is made while producing cement.

C. It takes less energy to produce fly ash than cement.

D. Fly ash is a costless by-product.

52. The word “mine” in the last sentence of the passage means_______.

A. to buy things from other countries

B. to search for useful materials in the mountains

C. to dig deeply into the ground to get useful materials

D. to take out certain materials from other things

【答案】

49---52 CDDC

【解析】略

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Have you ever wondered？

　　1．Why do airplanes take longer to fly west than east?

　　It can take five hours to go west-east from New York(NY)to London but seven hours to travel east-west from London to NY．The reason for the difference is an atmospheric phenomenon know as the jet(喷射)stream．The jet stream is a very high altitude wind which always blows from the west to the east across the Atlantic．The planes movement a constams air speed thus go faster in the west-east direction when the air moving with the wind than in the opposite direction．

　　2．What would happen if the gravity on Earth was suddenly turned off?

　　Supposing we could magically turn off gravity．Would buildings and other structures float away?What happened would depend on how strongly the things were attached to the Earth．The Earth is moving at quite a speed moving at over a thousand miles per hour．If you turn something round your head on a string, it goes around in a circle until you let go of the strong go of the string．Things not attacked to the Earth would fly off in a straight line．People in buildings would suddenly shoot upwards at a great speed until they hit the ceiling．Most things would fly off into space．

(1)

What information coa we get from the first passage?
[　　]
A．	tis the iet stoomn that affeets how fast airplanes fly．
B．	Planes go slower when they are moving with the wind．
C．	It takes more time to fly from NY to London than from London to NY．
D．	The jet stream always blows from the east to the west across the Atantic．

(2)

The word“shoot”underlined in the 2^nd passage probably means“________”．
[　　]
A．	send for
B．	move quickly
C．	come out
D．	grow quickly

(3)

It can be interred that without gravity ________．
[　　]
A．	buildings and other structures would float away
B．	trees and buildings would not so easily fly off
C．	something around your head would not float away
D．	everything outside buildings would fly off into space

(4)

Where can wemost probably read this text?
[　　]
A．	In s research paper
B．	In a tort story．
C．	In a travel magazine．
D．	In a student's book．

Have you ever wondered?

1.Why do airplanes take longer to fly west than east?

It can take five hours to go west-east from New York(NY) to London but seven hours to travel east-west from London to NY. The reason for the difference is an atmospheric phenomenon know as the jet(喷射) stream. The jet stream is a very high altitude wind which always blows from the west to the east across the Atlantic. The planes movement a constams air speed thus go faster in the west-east direction when the air moving with the wind than in the opposite direction.

2 What would happen if the gravity on Earth was suddenly turned off?

Supposing we could magically turn off gravity. Would buildings and other structures float away? What happened would depend on how strongly the things were attached to the Earth. The Earth is moving at quite a speed moving at over a thousand miles per hour. If you turn something round your head on a string, it goes around in a circle until you let go of the strong go of the string. Things not attacked to the Earth would fly off in a straight line . People in buildings would suddenly shoot upwards at a great speed until they hit the ceiling. Most things would fly off into space.

1.What information coa we get from the first passage?

A.tis the iet stoomn that affeets how fast airplanes fly.

B.Planes go slower when they are moving with the wind.

C.It takes more time to fly from NY to London than from London to NY.

D.The jet stream always blows from the east to the west across the Atantic.

2.The word“shoot”underlined in the 2nd passage probably means“__________”.

A.send for

B.move quickly

C.come out

D.grow quickly

3.It can be interred that without gravity_________.

A.buildings and other structures would float away

B.trees and buildings would not so easily fly off

C.something around your head would not float away

D.everything outside buildings would fly off into space

4.Where can wemost probably read this text?

A.In s research paper

B.In a tort story.

C.In a travel magazine.

D.In a student’s book.

Have you ever wondered?
1.Why do airplanes take longer to fly west than east?
It can take five hours to go west-east from New York(NY) to London but seven hours to travel east-west from London to NY. The reason for the difference is an atmospheric phenomenon know as the jet(喷射) stream. The jet stream is a very high altitude wind which always blows from the west to the east across the Atlantic. The planes movement a constams air speed thus go faster in the west-east direction when the air moving with the wind than in the opposite direction.
2 What would happen if the gravity on Earth was suddenly turned off?
Supposing we could magically turn off gravity. Would buildings and other structures float away? What happened would depend on how strongly the things were attached to the Earth. The Earth is moving at quite a speed moving at over a thousand miles per hour. If you turn something round your head on a string, it goes around in a circle until you let go of the strong go of the string. Things not attacked to the Earth would fly off in a straight line . People in buildings would suddenly shoot upwards at a great speed until they hit the ceiling. Most things would fly off into space.
1.What information coa we get from the first passage?
A.tis the iet stoomn that affeets how fast airplanes fly.
B.Planes go slower when they are moving with the wind.
C.It takes more time to fly from NY to London than from London to NY.
D.The jet stream always blows from the east to the west across the Atantic.
2.The word“shoot”underlined in the 2nd passage probably means“__________”.
A.send for
B.move quickly
C.come out
D.grow quickly
3.It can be interred that without gravity_________.
A.buildings and other structures would float away
B.trees and buildings would not so easily fly off
C.something around your head would not float away
D.everything outside buildings would fly off into space
4.Where can wemost probably read this text?
A.In s research paper
B.In a tort story.
C.In a travel magazine.
D.In a student’s book.