科研之友
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<正>在我们的印象中,螃蟹都是横着走路的。那么是否所有的螃蟹都是这样走路的呢?It is easy for us humans to move backwards, forward and sideways, this is because of how our legs are attached to our bodies. A crab’s legs, however, are attached to the side of its body. Its joints, unlike our knees, bend outwards, thus enabling the crab to only move sideways.
