题目类型：[单选] How should you signal the crane operator to hoist?().
A、With foremarm vertical and forefinfer pointing up ,move hand in small horizonal circles
B、With arm ertended downwards and forefinger pointing down,move hand in small horizontal crecles
C、Extend arm with fingers closed and thumb pointing upward
D、Place both fists in front of the body with the thumbs pointing outward
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参考答案: A
试题难度：★★☆
参考解析：