京津冀地区PM2.5主要来源于（）。
A.工业源和农业源
B.工业源和民用源
C.工业源和尾气排放
D.民用源和尾气排放
参考答案：B
When I met her at the entrance to the hall, she_________to me that she had seen me.
A．told
B．mentioned
C．referred
D．offered
按照差别待遇和特定的实施情况，关税可分为______
A．财政关税
B．进口附加税
C．差价税
D．特惠税
E．普惠税
