[单项选择]Cosmic rays of various kinds come through the air from outer space, but enormous quantities of radiation from the sun are ______ off.
A. avoided B. excluded C. screened D. separated

[单项选择]Cosmic rays of various kinds come through the air from outer space, but enormous quantities of radiation from the sun are（）off.
A. avoided
B. excluded
C. screened
D. separated

[单项选择]Summer has come, making us think of all kinds of nice things, such as holidays in the country.
The days are long and the nights are short, for the sun gets up early and goes to bed late in sunny June. It is one of the best and brightest months in the year. Birds sing all the day.
As night falls, the birds stop their song, one after another. However, they do not all sleep. When other birds are silent, a soft (轻柔) cry comes, then, after a few moments, louder. It is the nightingale (夜莺) singing his beautiful song.
The nightingale not only sings at night. On almost every warm day in early June, the little brown bird sings away on the roads and trees, but because all the other birds are also singing at the same time, we do not hear his voice so much. It is only at night, that we hear the nightingale at his best.

Why can’t people hear nightingale sing during the day
A. Because they only sing at night.
B. Because they don’t sing at all.
C. Because other birds are singing at the same time.

[填空题]X-rays and gamma rays can be used to detect and treat cancer ______.

[简答题]air carriers

[单项选择]Air France Tel: (010) 6588 1388 (020) 6360 6688 Day From To Flight Departure Arrival 1-7 Beijing Paris AF129 09:40 14:15 1-7 Paris Beijing AF128 15:55 07:40 2,4,7 Shanghai Paris AF111 10:55 17:05 1,3,6 Paris Shanghai AF112 15:55 09:05 Lufthansa Tel:(010) 6465 4488 (021) 6248 1100 Day From To Flight Departure Arrival 1-7 Beijing Frankfurt LH721 10:30 14:25 1-7 Frankfurt Beijing LH720
A. AF129.
B. AF128.
C. AF111.
D. AF112.

[简答题] Air Pollution When people think about air pollution, they usually think about smog, acid rain, CFC’’s, and other forms of outdoor air pollution. But did you know that air pollution also can exist inside homes and other buildings It can, and every year, the health of many people is affected by chemical substances present in the air within buildings. A great deal of research on pollution is being conducted at laboratories and universities. The goals of the research are to find solutions and to educate the public about the problem. Two places where this type of work is being done are LBNL and the University of California, Berkeley. Let’’s take a closer look at the various types of air pollution, the effects that they have on people, and what is being (or not being) done to correct the problem. What Is Air Pollution Air is the ocean we breathe. Air supplies us with oxygen which is essential for our bodies to live. Air supplies us with o