Dogs love splashing in mud and hippos wallow in it.狗喜欢在泥水洼里扑腾，河马则喜欢在其中打滚撒欢儿。Hippos are unable to submerge in the few remaining water holes.在仅剩的几个水坑里，河马根本无法没入水中。hippos wallowing in the river在河里打滚的河马...
Hippos are unable to submerge in the few remaining water holes...在仅剩的几个水坑里，河马根本无法没入水中。But exactly where hippos sit on the artiodactyl family tree has proved devilishly difficult to discern.河马也属于偶蹄目,这点专家并无异议,但是它们到底位在偶蹄动物演...