当火源的上风侧有遇险人员尚未撤出或不能确认遇险人员是否已牺牲,且矿井又不具备反风和改变烟流流向的条件时,保持正常通风。
参考答案:错
I'm very sorry to keep you _ so long. I have something important to do. [ ]
A. wait
B. waiting
C. waiting for
D. waited
和谐社会应当致力于在从源头上减少纠纷产生的基础上,通过建立完善的纠纷解决制度来公正、及时、妥善地解决所有纠纷。