单项选择题
A.长度不宜超过8米;重量不宜超过3.5吨B.长度不宜超过9米;重量不宜超过3.5吨C.长度不宜超过10米;重量不宜超过3.5吨D.长度不宜超过9米;重量不宜超过6吨
A.1.1倍,0.9倍B.1.2倍,0.9倍C.1.3倍,0.88倍D.1.4倍,0.88倍
A.上部B.下部C.外角D.内角