行走过程中一侧足跟着地至该侧足跟再次着地时所经过时间称为()。
A.步长
B.步频
C.步行周期
D.站立相
E.支撑相
参考答案:C
--Tom is such a stupid student that he had failed in every exam.
---Sorry, I won’t agree. He is ________ than stupid.
A.lazier
B.no lazier
C.more lazy
D.lazier rather
放电引起爆炸的条件是放电必须在爆炸性()物的爆炸浓范度围内发生。
A、有机
B、无机
C、物体
D、混合