在验证机械能守恒定律的实验中，下列说法正确的是（） A_爱下问搜题

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问题多选题

在验证机械能守恒定律的实验中，下列说法正确的是（　　）

A．要用天平称重锤质量

B．选用质量大的重锤可减少实验误差

C．实验结果总是动能增加略小于重力势能的减少

D．实验结果总是动能增加略大于重力势能的减少．

答案

BC

完形填空

It was an early morning in summer. In the streets, sleepy-eyed people were moving quickly, heading towards their    . This was the beginning of another      day in New York City.      this day was to be different.
Waiting     the crowded streets, on top of a       110 stories high, was Philippe Petit. This daring Frenchman was about to     a tightrope (绷索) between the two towers of the World Trade Center.
Philippe took his first      with great care. The wire held. Now he was     he could do it.     only a balancing pole, Philippe walked his way across, a      of 131 feet.
　Soon the rush-hour     began to notice. What a      ! There, 131 feet above the street, a      figure was walking on air.
　Philippe made seven      , back and forth (来回). He wasn't satisfied with just      . At times, he would turn, sit down, and     go on his knees. Once, he had the astonishing     to lie down on the thin thread. And thousands of      watchers stared with their hearts beating fast.
　After the forty-five-minute     , Philippe was taken to the police station. He was asked     he did it. Philippe shrugged (耸肩) and said, "When I see two tall buildings, I walk."

A．experiments

单项选择题

设计概算编制依据不包括( )。

A．初步设计项目一览表
B．施工现场测定资料、试验资料和统计资料
C．资金筹措方式
D．能满足编制设计概算的各专业设计图样、文字说明和主要设备表