四冲程发动机在一个工作循环中，曲轴转 2 圈，活塞在汽缸里往复（）次，进、排气门各开闭（）次。
萜类
如何利用首因效应来给他人塑造良好的第一印象？
On the WLSE， which of the following fault policies would be used to verify that access to thecommand-line interface of the access point is secure？（） ["registration error","authentication failures threshold","HTTP disabled","Telnet disabled"]
采掘工作面的空气温度超过（）℃、机电设备硐室的空气温度超过34℃时，必须停止作业。 ["32","28","30"]
自杀
