part of 一部分,部分的 例如：He received part of his education in England.
他有一部分教育是在英国接受的.
a part of 一部分,一小部分 a great part of 大部分
例如：He spends at least a part of his time in reading.
他至少有一部分空闲时间看书.
When it becomes not a part of your life but your entire life.
当它不是你生活的一部分而是变成你的全部生活的时候.
parts of 部分的,一部分例如：I was in touch with those parts of myself because of the experiences I had with my father.But we all have it.
我因为和我父亲的经历,可以触及到内心的这个部分,但其实每个人都可以的.
区别主要在于后面接的是什么,以及单复数等.