检查可燃气体报警控制器的功能，当故障报警和气体泄漏报警同时发_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题单项选择题

检查可燃气体报警控制器的功能，当故障报警和气体泄漏报警同时发生时，哪个应优先报警？（）

A、故障报警

B、都不报警

C、气体泄漏报警

D、同时报警

答案

参考答案：C

选择题

Only when he returned from the exchange program ________ how much he enjoyed it.[ ]

A. he knew

B. he had known

C. did he know

D. had he known

问答题简答题

说明何谓简单运动？何谓复合运动？其本质区别是什么？