[单项选择]（　） no gravity, there would be no air around the earth.
A. Were there
B. There were
C. Was there
D. There be

[单项选择]An energy tax would curb ordinary air pollution, limit oil imports and cut the budget ______
A. disposition B. discrepancy C. defect D. deficit

[单项选择]There would be no air pollution to this city because ______.
A. there was a special plant to treat the polluted air
B. the city was away from the mainland
C. people in the city did not burn oil or coal
D. vehicles there were powered by electricity

[单项选择]Without air resistance, all objects would fall at the same speed ________ their weight.


A. regardless of
B. instead of
C. according
D. despite of

[单项选择]Cold air causes the arteries around the heart to constrict.


A. become rigid
B. contract
C. close
D. die

[单项选择]Helen said she would like to go to Atlanta by air, but I wonder if she has enough money to pay for the______.


A. travel
B. tourism
C. journey
D. course

[单项选择]Without air, there would be no______.


A. shelters
B. volcanoes
C. weather
D. springs

[单项选择]（　）no air or water, there would be no life in the world.
A. There was
B. There were
C. Is there
D. Were there

[单项选择]ff the soldiers move to that area, they would be exposed ______ great danger.
A. with
B. by
C. to
D. in

[单项选择]Air cannot ______,but it is all around us.


A. is seen
B. see
C. be seen

[单项选择]（）no air or water, there would be no life in the world.
A. There was
B. There were
C. Is there
D. Were there

[单项选择]E Around the world more and more people are taking part in dangerous sports and activities．Ofcourse．there have always been people who have looked for adventures——those who have climbed the highest mountains，traveled into unknown parts of the world or sailed in small boats across the greatest oceans．Now，however，there are people who look for an immediate excitement from a risky activity which may only last a few minutes or even seconds． 1 would consider bungee jumping to be a good example．of such an activity．You jump from a high place(perhaps a bridge or a hot—air balloon)200 metre8 above the ground with an elastic(有弹性的)rope tied to your ankles．You fall at up t0 150 kilometres an hour until the rope stops you from hitting the ground．It is said that about 2 million people around the world have now tried bun-gee jumpin9．Other activities which most people would say are as risky as bungee jumping include jumping from tall building and diving into the sea from the top of high cliff(悬崖
A. Dangerous sports：what and why
B. The boredom of modem life
C. Bungee jumpin9：Is it really dangerous
D. The need for excitement

[单项选择]______ the car accident, they would have arrived earlier.
A. Except for
B. But for
C. Besides
D. Save for

[单项选择]It is widely believed that the pull of gravity on a falling raindrop changes ______ round shape into a teardrop shape．

[单项选择]Newton's theory of gravity was corrected by Einstein's theory because of ______.

[单项选择]Dating from around
A. A．D. 1000,the largest mound surviving from the Mississippian culturewas one hundred feet high and had a base of nearly fifteen acres. civilization

[单项选择]Bob assured his boss that he would ______all his energies in doing this new job.


A. call for
B. call off
C. call forth
D. call on