A.2倍 B.21/2倍 C.31/2倍 D.1倍,即截面相等
A.1倍 B.3-1/2倍 C.1/3倍 D.1/2倍
A.少計(jì)1/3 B.少計(jì)2/3 C.倒計(jì)1/3 D.不計(jì)