some… others，others 和some, others, still others

some后面接的只有others复数

There are many people in the park; some are walking, others are jogging, and still others are doing exercise.
公园里有很多人，有的在散步，有的在慢跑，还有的在做操。

People vary in taste; some love music, some enjoy taking pictures, and still others are fond of hiking.
每个人嗜好不同，有人喜欢音乐，有人喜欢摄影，还有些人喜欢爬山。 some others 与 some the others的区别
There are 5 pencils, some are red, the others are blue.
There are many boys here, some are 18 years old, others are 20 years old.
从上述两句句子中可以看出：如果有限定范围的，比如第一句有5只笔，那么就要用some the others,如果没有限定范围，如第二句many boys一个模糊的数量，就用some others
One...the other...another
这种结构限定在有三样东西并列比如I have three pens, one is blue, the other is red and another is yellow.
One...the other
这种结构限定在有两样东西并列比如I have two pens, one is blue, the other is red.

标准用法是some others

例如 some are happy, others are sad
有的时候可以倒装 others are sad while some are happy

没有still others这个用法