使用手电钻时必须戴绝缘手套，换钻头时须拔下插头。
参考答案：对
- When we are in danger, we need to stay_______.
- Exactly. Only in this way can we come up with good ideas.
A．still
B．quiet
C．calm
D．silent
气胀式救生筏及其静水压力释放器检修证明书的有效期不超过（）个月。
A.6
B.10
C.12
D.17
