库房管理中登帐时，应使用（）笔。
A、蓝、黑墨水
B、铅笔
C、圆珠笔
D、都可以
参考答案：A
Mr. Smith was thinking about how to explain to the manager why he was late for work, when a good idea ______ to him.
A．happened
B．brought
C．occurred
D．struck
电力线的根数与（）成正比，与介质的（）成反比。
