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举一反三
【单选题】（）是用自然或机械的方法向某一房间或空间送入室外空气，和由某一房间或空间排除空气的过程，送入的空气可以是经过处理的，也可以是不经过处理的。
A.
排风
B.
通风
C.
新风
D.
回风
【单选题】有两个金属球，一个是半径为2R的空心球，另一个是半径为R的实心球，两球间的距离r>>R。空心球原来带有电荷量+2Q，实心球原来带有电荷量+2Q。若用细导线将它们连接起来，那么电荷是怎样分配的？
A.
均带
B.
不发生变化。
C.
空心球带电
，实心球带电
。
，实心球带电
。D.
空心球带电+Q，实心球带电+3Q。
【单选题】Dreams of Flight The story of man's dream of flight, of his desire to reach the stars, is as old as mankind itself. According to Greek legend, Daedalus was the first man to fly. He and his son had bee...
A.
He killed the guards and got out of the island.
B.
A god came to rescue him and took him away.
C.
His son came to rescue him and took him away.
D.
He made wings of wax and flew away from the island.