Having checked the doors were closed,and_______all the lights were off,the boy opened the door to his bedroom.

A．why

B．that

C．when

D．where

压力容器受压部件在使用中由于各种原因造成的介质泄漏被迫停车进行维修的或由于容器泄漏而引起（）的事故称为泄漏事故。

A、火灾

B、人员中毒

C、设备损坏