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问题 选择题

对于万有引力的表达式F＝G，下列说法正确的是    

A．公式中的G为万有引力常量，它是由实验得出的，而不是人为规定的

B．当r趋近于零时，万有引力趋近于无穷大

C．m1和m2受到的引力总是大小相等，而与m1、m2是否相等无关

D．m1与m2受到的引力总是大小相等、方向相反，是一对平衡力

答案

AC

万有引力的应用条件为两质点间的作用力，当r趋近于零时，两物体不能再看做质点，B错；m1与m2受到的引力总是大小相等、方向相反，是一对相互作用力，D错；

单项选择题 B型题

在动脉瘤诊断中，最有价值的方法是（）

A.2cm

B.选择性动脉造影

C.手术治疗是唯一有效的方法

D.5cm

E.1991
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填空题

According to historical records，the first (1) Olympic Games can be traced back to 776 BC.They (2) dedicated to the Olympian gods and were staged on the (3) plains of Olympia.They continued for nearly 12 centuries， (4) Emperor Theodosius decreed in 393 A.D.that aU such"pagan cults" (5) banned.
The oldest myth which concerns the beginning of the (6) Games is that of Idaios Daktylos Herakles.According to other (7) ，Zeus，the father of humanity，fought and defeated Cronus in a (8) for the throne of the gods.Finally，the well-known (9) Herakles is mentioned who staged games in Olympia in honour (10) Zeus,because the latter had helped him conquer Elis when (11) went to war against Augeas.
Through the 12 centuries of (12) Olympic Games，many wonderful athletes competed in the stadium and (13) hippodrome of ancient Olympia’s sacred area，moving the crowds with (14) great achievements.Although mortal，their Olympic victories immortalised them.Of (15) best athletes who left their mark on the sacred vallev (16) Olympia，some surpassed all limits and became legends by winning (17) successive Olympic Games and remaining at the forefront of their (18) for more than a decade.
The ancient Olympic Games were (19) a one.day event until 684 BC.when they were extended (20) three days.In the 5th century B.C.，the Games were extended again to cover five days.
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