Two is enough ,为什么谓语动词用的是单数呢?而 Ten of them are teachers 却是复数

Two is enough ,为什么谓语动词用的是单数呢?而 Ten of them are teachers 却是复数 十分之一是 one out of ten 还是 one in ten?他们的谓语动词是单数还是复数? two-thirds of a cake 后的谓语动词是单数还是复数? half of the two people 后面的谓语动词是复数还是单数? neither of them 还有none of them 后面的谓语动词用单数还是复数 two slices of bread 的谓语是单数还是复数 this kind of trees is/are rare?主语是kind 还是trees,谓语动词应该用单数复数? Neither of them 后谓语动词用单数还是复数, two piece of news ,谓语动词用复数还是单数? two kinks of paper ...谓语动词用单数还是复数? one of the加可数名词复数后面的谓语动词是用复数还是单数 the rest of the world 后面的谓语动词用单数还是复数呢?（意思是世界上其他人）