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

A.With forearm vertical and forefinger pointing up，move hand in small horizontal circles
B.With arm extended downwards and forefinger pointing down，move hand in small horizontal circles
C.Extend arm with fingers closed and thumb pointing upward
D.Place both fists in front of body with the thumbs pointing upward

A.exposure to inclement weather conditions
B.carelessness
C.the use of improper gear
D.moisture caused by condensation

A.Keep the loads as close to the rail or deck as possible
B.If cargo is likely to settle，make provisions to secure it after it has settled
C.Thoroughly secure and shore all cargo so that it cannot move
D.hen stowing cargo，avoid leaving empty paces