无码高清视频|成人自拍视频|欧美成人午夜无码A片秀色直播|草美女视频网站|美女被操网站在线观看

單項(xiàng)選擇題

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 fists in front of the body with the thumbs pointing upward
C.With forearm vertical and forefinger pointing up,move hand in small horizond circles
D.Extend arm with the fingers closed and thumb upward

微信掃碼免費(fèi)搜題