平衡接触角是度量可浮性的一个物理量，其大小与矿物的可浮性成（）。
A、正比
B、反比
C、无关
参考答案：A
As a new graduate, he doesn't know ___________ it takes to start a business in his hometown. [ ]
A. how
B. when
C. what
D. which
小于24V的电压为安全电压。
