某次刮大风时把一棵大树吹倒了,需要两个工人把它扶起,工人们想

某次刮大风时把一棵大树吹倒了,需要两个工人把它扶起,工人们想到了如图l2所示的四种方案,每个人所需拉力最小的方案是    (    )

答案

B

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