单项选择题
A.50,5,内高外低; B.60,5,外高内低; C.70,10,内高外低; D.80,10,外高内低;
A.2.2,低于; B.2.2,高于; C.2.0,低于; D.2.0,高于;
A.1.2; B.1.5; C.1.8; D.2.0;