3．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 （大氣現(xiàn)象） known as the jet stream （氣流）．The jet stream is a very high altitude （=above sea level） wind which always blows from the west to the east across the Atlantic．So the planes moving at a constant air speed go faster from the west to the east when they are moving with the wind than in the opposite．
2．What would happen if the gravity on Earth was suddenly turned off？
Supposing we could magically turn off gravity．Would buildings and other buildings float away？What happened would depend on （依靠） how strongly the things were attached （吸附） 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，it goes around in a circle until you let go of the string．Then it flies off in a straight line．‘Turning 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 up at a great speed until they hit the ceiling （=top surface of a room）．Most things outside would fly off into space．
32．What information can we get from the first part？A
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．
33．The underlined word"shoot"in the 2nd part means"B"．
A．send for
B．move quickly
C．come out
D．grow quickly
34．Which of the following is NOT mentioned in the passage？C
A．It takes seven hours to travel from London to New York．
B．The earth is moving at a high speed．
C．People on the earth will grow higher if there's no gravity．
D．Things not attached to the earth would fly off in a straight line．
35．Where can we read this passage？D
A．In a comic book．
B．In a short story．
C．In a travel magazine．
D．In a student's book．
