题干

如图所示,两颗个人造地球卫星A、B围绕地球E做匀速圆周运动,卫星A的轨道半径为rA,运行周期为TA;卫星B的轨道半径为rB.已知万有引力常量为G.则根据以上信息可以求出(   )

A:卫星B的运行周期

B:地球的质量

C:地面上的重力加速度

D:地球的半径

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答案(点此获取答案解析)

A,B

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阅读理解

“The first and best of victories for a man is to conquerhimself; to be conquered by himself is, of all things, the most shameful,” saysPlato. Self-control is at the root of all the advantages. Let a man give in tohis impulses (冲动) andfeelings, and from that moment he gives up his moral freedom.

A single angry word has lost many friends. When Socrates foundin himself any temper or anger, he would check it by speaking low in order tocontrol himself. If you are conscious of being angry, keep your mouth shut sothat you can hold back rising anger. Many a person has dropped dead in greatanger. Fits of anger bring fits of disease. “Whoever the gods would destroy,they first make them mad.” “Keep cool,” says Webster, “anger is notargument.” “Be calm in arguing,” says George Herbert, “for fierceness (狂怒) makes error a fault.”

To be angry with a weak man is to prove that you are not strongyourself. “Anger,” says Pythagoras, “begins with foolishness and ends withregret.” You must measure the strength of a man by the power of the feelings heconquers, not by the power of those which conquer him.

Self-control is man’s last and greatest victory.

If a man lacks self-control he seems to lack everything. Withoutit he can have no patience, no power to govern himself; he can have noself-confidence, for he will always be controlled by his strongest feeling. Ifhe lacks self-control, the very backbone and nerve of character are lackingtoo.