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【单选题】
听力原文：M: Well, Sally. Why do you look unhappy? W: Oh, Hill, I have just had a quarrel with Mr. Smith. M: What on earth was it about? W: Well, I have made three bad mistakes so far this week, so he got very angry with me. M: But I don't understand. You are usually very careful and never make mistakes. W: I'm just so tired. I don't know what I'm doing. M: Why? Have you been going to bed late these days? W: No, I'm usually in bed at about eleven. But I've been woken up at about half past four every morning. And then I cannot go back to sleep again, M: Why? W: It's my new neighbor, the milkman next door. He gets up at half past four and he always turns the radio on loudly. And it's difficult to ask him to mm it down. I don't know him yet. M: If you don't want to see him, write him a letter. I'U help you write the letter. W: OK. Let's try. Why was Sally unhappy?A.
She could not sleep at night.
B.
She could not talk to the milkman.
C.
She had quarrelled with Mr. Smith.
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【多选题】以下说法正确的是：
A.
平面运动刚体的动能等于随质心的平移动能，加上绕质心的转动动能；
B.
刚体对z轴的转动惯量，等于它对经过质心且与z轴平行的轴的转动惯量，加上刚体质量乘以两轴之间垂直距离的平方；
C.
圆轮作纯滚动时，静摩擦力不做功；
D.
平面运动刚体的动能，等于它绕速度瞬心轴的定轴转动动能；
E.
力系中各成员力对刚体做的功，等于该力系向刚体上任意一点简化后的主矢力与主矩力偶做功的和；
F.
平移前的力对刚体做的功，等于平移后的力对刚体做的功加上力平移时所产生附加力偶对刚体做的功；
【简答题】1进给量: 工件或刀具每转一转或往复一次或刀具每转过一齿时,工件与刀具在进给方向上的相对位移。 2.切削速度:主运动的线速度。 3.切削厚度:垂直于工件过渡表面测得的切削层尺寸。 4.切削宽度:平行于工件过渡表面测得的切削层尺寸。 5.切削层面积: 切削层截面的面积。
【简答题】人从一定高度落地容易造成骨折.一般成人胫骨的极限抗压强度约为1.5×10 7 N/m 2 ,胫骨最小横截面积大约为3.2 cm 2 .假若一质量为50 kg的人从一定高度直膝双足落地,落地时其重心又约下降1 cm,试计算一下这个高度超过多少米时,就会导致胫骨骨折?
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