阅读理解
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．
