some people指‘某些人’.
如果用some of后面跟一个名词,就是指某一类东西/人中的一部分.那么,后面这个名词是要有限定的.所以,通常后面的这个名词前面有个the(除非前面有个所属格代词).例如：
Some of the passengers on the bus were injured.(the passengers有自己的限定,即on the bus,不是随便的什么乘客.)
Some of my books were bought by my mum.
再看下面的句子：
Some students are hardworking and some are not.
Some of the students in this class are very hardworking.