单项选择题
A.C30B.C20C.C15D.C10
A.100mm;300mmB.200mm;200mmC.300mm;100mmD.400mm;200mm
A.导轨;滑轮B.拉杆;滑轮C.导轨;拉杆D.制动杆;拉杆
A.50B.70C.80D.100
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