A.2 B.3.5 C.6 D.8
A.當(dāng)?shù)趸\超速下降時(shí)制動 B.當(dāng)?shù)趸\超速上升時(shí)制動 C.當(dāng)鋼絲繩斷裂時(shí)制動 D.當(dāng)升降機(jī)電源斷電時(shí)制動
A.10 B.20 C.30 D.40