Most pedestal crane power is provided by（）.

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

A.Use one hand to give any motion signal，and place the other hand motionless in front of the hand giving the motion signa
B.Extend arm with the thumb pointing up，and flex the fingers in and out for as long as the load movement is desired
C.First tap your elbow with one hand and then proceed to use regular signals
D.First tap the top of your head with your fist and then proceed to use regular signals

A.Extend arm and point finger in the direction to move the boom
B.Extend arm with thumb pointing downward and flex fingers in and out
C.With forearm vertical and forefinger pointing up，move hand in small horizontal circles
D.With arm extended downwards and forefinger pointing down，move hand in small horizontal circles