单项选择题
A.面积比1.99,内间隙比0.99 B.面积比12.8,内间隙比1.99 C.面积比12.8,内间隙比0.99 D.面积比0.99,内间隙比12.8
A.6.48m/d B.8.67m/d C.10.45m/d D.12.01m/d
A.1.80m B.2.80m C.3.80m D.4.80m