A.7t B.7.5t C.8t D.12.5t
A.5t B.8t C.11t D.10t
A.吊桿的仰角 B.吊貨滑車(chē)組的滑輪數(shù)目m C.吊桿自重G D.吊貨滑車(chē)組滑輪摩擦力