当维护机电设备安全的（）因紧急情况工作时，应发出声光报警装置。
参考答案：安全系统
The engineers are so busy that they have no time for outdoor sports activities，________ they have the interest.
A．wherever
B．whenever
C．even if
D．as if
RIP的最大跳数是( )：
A．24
B．18
C．15
D．12
