国家关于发展热电联产规定，单机容量在50 MW以下的热电机组，其热电比年平均应大于( )。
A．70%
B．80%
C．90%
D．100%
参考答案：D
— Did you know any French before you arrived in Washington?
— Never ____ it, actually.
A．had I learned
B．have I learned
C．I learned
D．would I learn
为防止现场残留火种可能引发火灾爆炸，撤离现场时应注意什么？
