《环境空气质量标准》（修改版）中，臭氧的二级标准的1h平均浓度限值是（）mg/m³。

A.0.20

B.0.02

C.0.05

D.0.06

．She is fed up with sharing a house with others;           , she is looking for her own flat.

A．moreover

B．otherwise

C．however

D．therefore