在大气污染源调查一级评价项目中,周期性排放系数取值为()。
A.0-1
B.1~2
C.1.5
D.1~3
参考答案:A
I think you probably know China has adopted a flexible policy( )her foreign trade.
A.on
B.with
C.in
D.under
DNA三级结构的生物学意义是什么?