試題詳解

13.How should you signal the crane operator to RAISE the boom?
(A)Extend arm with the thumb pointing up and flex the fingers in and out.
(B)Place both fits in front of the body with the thumbs pointing upward.
(C)With forearm vertical and forefinger pointing up, move hand in small horizontal circles.
(D)Extend arm with fingers closed and point thumb upward.