通常情况下，下列物体或物质中属于导体的是： [ ]
A.空气
B.蒸馏水
C.铅笔芯
D.橡胶手套
答案：C
(2013·河北衡水中学模拟)Some young people these days just ________ go out of their homes to contact the real world.
A．mustn't
B．won't
C．mightn't
D．shouldn't
塑编企业常用的GK8-2缝纫机（）可达1300rpm，功率为0.40kw。
A.力矩
B.转速
C.线速度
D.角速度
