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【单选题】
第二次鸦片战争爆发的根本原因是列强要( )。A.
增加沿海通商口岸
B.
进一步打开中国市场，扩大侵略权益
C.
允许外国人在内地自由贸易
D.
利用亚罗号事件和马神甫事件
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举一反三
【单选题】Running an electric winch at slow speed over a long period of time causes ______．
A.
the speed to be retarded by the friction brake
B.
a load to go downward at full speed
C.
the circuit breaker to turn off
D.
the resistors to overheat and ually burn out
【单选题】If an electric cargo winch is being used to lift a draft of cargo and the engine room loses all power，which will occur ________．
A.
A pawl，forced by a spring mechanism，will engage the teeth of the bull gear and hold the load
B.
An electromagnetic brake will hold the load where it is suspended
C.
The load will fall rapidly to the deck unless the foot brake is engaged
D.
The load will slowly lower to the deck under control of the drag of the winch motor
【简答题】比一比。 30分○30秒 1时○60秒 60分○1时 1分○61秒
【简答题】80分=（ ）时（ ）分 60秒=（ ）分 1分40秒=（ ）秒
【单选题】If an attempt is made to hoist a load that exceeds the capacity of an electric winch，an overload safety device causes a circuit breaker to cut off the current to the winch motor ______．
A.
when the line pull reaches the rated winch capacity
B.
after the line pull exceeds the rated winch capacity
C.
after a short build-up of torque
D.
immediately
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