some of them 为什么要用them?

some of them 为什么要用them? I know some of them 中为什么要用them? many of them are young and some are old 为什么要用some Some of them are Both of them study very hard.为什么要用them? 英语语法,定语从句This would save the life of many animals,some of which have almost die.为什么不能说成some of them?到底什么时候用some of them呢?请详细说明他们之间的用法差别, some of them are very nice some of 后为什么用宾格?》 some of them怎么用可以这样用么some wonders of them some 加名词of them还是 some of the wondersi know some wonders of them我知道这些名胜中的一些 这句怎么改 some of them are red.some of them are yellow. Here are some of them. some of they还是them? Some of them 如何读? some of them怎么读 请问 some of them are students 这句话当中为什么用them而不用they?看了一些其他类似问题的回答 网友说因为of是介词 后面要跟宾语 所以用宾格的them,还说them是of的宾语 .我不太明白 如果说介词后面 He wrote down some data,some of them quiet familiar.这句话中的them后为什么不加are? 为什么:They picked up some rocks and put (them)in the spacesship,为什么要用them呢? 并列句不是要相同的时态吗.I bought some book,and all of them are interesting.为什么前面用过去时后面用一般现在时呢. The manager of them prepares some beautiful gifts.The manager of them可以这样用吗