mankind前不可加任何限定词,但可用形容词修饰.它是集合名词,可作单数或复数使用.作单数概念时,谓语要用单数,其相应的代词一般为it,its,itself(也有人用he ,him,his,himself);作复数概念时,谓语要用复数,其相应的代词是they,them,their,themselves.例如：Mankind is much cleverer than it was one thousand years ago.人类比一千年前是聪明多了.All progressive mankind love peace.所有进步人类都热爱和平.That is one small step for a man,but one giant leap for mankind.对于个人来说那是小小的一步,但对于整个人类来说却是一次巨大的飞越.
human being也可表示“人类”,它是可数名词,有单复数之分.其意义比较具体,它一般用来区别人以外的事物,特别是动物或者是“神”,“鬼”之类.例如：Without its light and warmth there would be neither plants nor animals nor human beings.没有光和热,就不可能有植物,动物,也不可能有人类.Although the Negroes were human beings just like the whites,they were not treated as humanbeing.尽管黑人和白人一样都是属于人类,但是他们并没有被当作人对待.
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