单项选择题
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
单项选择题 How should you signal the crane operator to move slowly（）.
单项选择题 How should you signal the crane operator to lower the boom and raise the load（）.
单项选择题 How should you signal the crane operator to hoist（）.
