不平衡的旋转零、部件运转时（）。
A、使用寿命长
B、不影响工作精度
C、产生剧烈振动
D、振动噪音小
参考答案：C
"She's not a dancing teacher, is she?" "________."
A．Yes, and she isn'
B．Yes, but she was
C．No, but she isn't
D．No, but she was
环境条件对工程质量产生特定的影响。
