[单项选择]

Without the sun. them would be no weather. Light from the sun not only causes sunny days. but it also causes weather to be different in different parts of the world. The sun causes all other kinds of weatber. inckiding wind. rain. and even snow.

Ligth from the sun can make both good weather and bad days. A. True. B. False.

[单项选择]Without computer network, it would be impossible to carry on ______any business operation in the advanced countries.
A. practically
B. preferably
C. precisely
D. possibly

[填空题]Without greenhouse effect, Earth would be colder by about ______.

[单项选择]

Without the atmosphere, there would be no weather, no wind, rain, snow, or clouds. Air is all around us; we live at the bottom of a great ocean of air. It is invisible, but we can feel it when it moves. There are miles of all above us, pressing down with great weight on the earth and everything on it. Because air presses down on us from all directions at the same time, and because we are able to bear (忍受) this weight, we do not seem to feel it. But scientists have proved that air has this weight, and that anything that has weight creates (产生) a force called pressure. As changes in air pressure take place, they make air move.
Air is a gas that expands (膨胀) when heated, gets lighter, and moves upward. When air is cooled, it gets heavier, sinks close to the earth’s surface, and flows like water in a great river. As warm air rises, cold air rashes to take its place. Thus winds originate (起源). The winds that blow high above us are caused by the warmer air running away fr
A. why we don’t feel air
B. why atmosphere is important to us
C. why there is air surrounding us
D. why there is air pressure

[单项选择]Without the music, the children would have not had so much fun.（）
A. wouldn’t be having
B. wouldn’t have been
C. wouldn’t be
D. wouldn’t have had