Number + 部分 + (的 + Noun)
The word 部分 (bùfen) means 'part' or 'portion' and is used to refer to a section or component of a whole. When preceded by the number 一 (one), the phrase 一部分 means 'a part of.' It is commonly used in constructions like 一部分人 (some people) or with 的 to indicate belonging.
只有一部分学生通过了考试。
Zhǐyǒu yī bùfèn xuéshēng tōngguò le kǎoshì.
Only some of the students passed the exam.
这笔钱的一部分用来交房租。
Zhè bǐ qián de yī bùfèn yòng lái jiāo fángzū.
Part of this money is used to pay rent.
大部分时间我都在家工作。
Dà bùfèn shíjiān wǒ dōu zài jiā gōngzuò.
I work from home most of the time.