一部 jat¹ bou⁶ {yī bù}

Radical 1, [measure word] a thing, usually used with object or thing like cellphone or movie

一部份 jat¹ bou⁶ fan⁶ {yī bù fèn}

A part

一部分 jat¹ bou⁶ fan⁶ {yī bù fèn}

1. portion
2. part of
3. subset

一部二十四史，不知從何說起〔---------从-说-〕 jat¹ bou⁶ ji⁶ sap⁶ sei³ si², bat¹ zi¹ cung⁴ ho⁴ syut³ hei² {yī bù èr shí sì shǐ , bù zhī cóng hé shuō qǐ}

It's a long and intricate story, I hardly know where to start.