human humanbeings区别
human强调“人群”，human being强调的是“个人”。 总体上： human=human beings； 另外，human有单数，a human ; human的复数变化是humans Its rate of growth was fast — much more like that of an ape than that of a human. 它的发育速度很快——更像猿，而不像人。 Each human being has to die, but mankind goes on...