设备运行保养，指设备（）时的保养。
参考答案：正常运行
She couldn't help, even though she tried not to,（）at the strange clothes her friend was wearing.
A. to laugh
B. laugh
C. laughing
D. laughed
在工作时，私人电话，应在二分钟内结束通话。（）
A.正确
B.错误
