单项选择题
A.Shall B.Are C.Is D.Be
（）is the rate of discharging here?A.WhenB.WhyC.WhatD.Ei...
单项选择题（）is the rate of discharging here?
A.When B.Why C.What D.Either A or B
The （）of the derrick is out of order.A.blackB.backC.blo...
单项选择题The （）of the derrick is out of order.
A.black B.back C.block D.broken
Renew a cargo runner, please. （）A.fallB.stayC.guyD.slin...
单项选择题Renew a cargo runner, please. （）
A.fall B.stay C.guy D.sling
