ydlj Have you ever wondered? 1.Why do a

题目：

ydlj

                                                      Have you ever wondered?

1.Why do airplanes take longer to fly west than east?, It can take five hours to go westeast from New

York (NY) to London but seven hours to travel eastwest from London to NY.The reason for the

difference is an atmospheric phenomenon known 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 moving at a

constant air speed thus go faster in the westeast direction when they are 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(细绳), 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 attached 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 outside

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 inferred 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 a research paper.

B. In a short story.

C. In a travel magazine.

D. In a student's book.