A、<img width="13" height="37" src="http://admintk.100xuexi.com/UpLoadImage/2016-08-19/19b2ab83-3d4c-4b57-9ac1-fdaf3fa46135.png" />
B、<img width="13" height="36" src="http://admintk.100xuexi.com/UpLoadImage/2016-08-19/c807c690-e385-4a59-b8ac-40fb91476f98.png" />
C、1.5
D、3