A.結(jié)構(gòu)簡(jiǎn)單 B.起重噸位大 C.起升幅度大 D.起重噸位和起升幅度大
A.2′ B.3′ C.4′ D.5′
A.3%~5% B.5%~8% C.8%~10% D.10%~12%