研究机械平衡的目的是部分或完全消除构件在运动时所产生的惯性力和惯性力偶矩。
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刚性转子的动平衡必须选两个平衡平面。
A. 对
B. 错
unsure (Para. 1, Line 4): ______
A. doubtful
B. clear
C. knowledgeable
acquaintance (Para. 2, Line 2): ______
A. stranger
B. a person whom one knows but do not know well
C. expert in one field
significance (Para. 2, Line 4): ______
A. basic knowledge
B. importance
C. evaluation