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6、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（噴射）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 constants 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（建筑物） 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 around your head on a string（細(xì)繩），it goes around in a circle until you let go of the string．Then it flies off in a straight line．‘Switching off’ gravity would be like letting 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 can we get from the first passage?

A．It is the jet stream that affects 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 Atlantic．

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 we most probably read this text?

A．In s research paper                                     B．In a short story．

C．In a travel magazine．                                 D．In a student’s book．