摘要：填空 (1)-22= 2= 0= (4)20= ( 5)2 -3= ( 6)(-2) -3=
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填空：
（1）21-20=
（2）请用字母表示第n个等式，并验证你的发现．
（3）利用（2）中你的发现，求20+21+22+23+…+219+220的值．
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（1）21-20=
1
1
=2（ ）；22-21=2
2
=2（ ）；23-22=4
4
=2（ ）（2）请用字母表示第n个等式，并验证你的发现．
（3）利用（2）中你的发现，求20+21+22+23+…+219+220的值．
填空：
（1）21-20=______=2；22-21=______=2；23-22=______=2
（2）请用字母表示第n个等式，并验证你的发现．
（3）利用（2）中你的发现，求20+21+22+23+…+219+220的值．
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完形填空 （20分）
The famous British inventor George Stephenson was born in 1781 and died in 1848. one of his _21_ important inventions was the train. He _22_his first train when he was forty-four years old. When he was experimenting with the _23_ engine on the train, he met with _24_ from the government, newspapers and the gentlemen in the country. They said that the noise and the smoke would _25_ cows, horses and sheep, that the _26_ would hurtle(炸飞) or that the hot coals from it would _27_their houses. At that time, _28_ people believed what they said.
George Stephenson _29_ the people that the train could go on small _30_, could pull carriages _31_goods and passengers and there was _32_ to them. It was a very _33_ matter for him to _34_ them believe. However, after _35_, he was able to do it; and the first train that _36_ by Stephenson himself _37_ what he had said.
The first day _38_ the people along the way _39_ the noises of the train _40_ and saw it running quickly to them, they ran back home as quickly as they could and closed their doors tightly, for they thought it a genius. They did not dare to come out until it had passed.
【小题2】made B. bought C. introduced D. did
【小题10】 A.reads B. rivers C. steam D rails
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The famous British inventor George Stephenson was born in 1781 and died in 1848. one of his _21_ important inventions was the train. He _22_his first train when he was forty-four years old. When he was experimenting with the _23_ engine on the train, he met with _24_ from the government, newspapers and the gentlemen in the country. They said that the noise and the smoke would _25_ cows, horses and sheep, that the _26_ would hurtle(炸飞) or that the hot coals from it would _27_their houses. At that time, _28_ people believed what they said.
George Stephenson _29_ the people that the train could go on small _30_, could pull carriages _31_goods and passengers and there was _32_ to them. It was a very _33_ matter for him to _34_ them believe. However, after _35_, he was able to do it; and the first train that _36_ by Stephenson himself _37_ what he had said.
The first day _38_ the people along the way _39_ the noises of the train _40_ and saw it running quickly to them, they ran back home as quickly as they could and closed their doors tightly, for they thought it a genius. They did not dare to come out until it had passed.
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