To do so, I divided the book into two parts. In part one, I describe the philosophical foundations of digital minimalism, starting with an examination of the forces that are making so many people’s digital lives increasingly intolerable, before moving on to a detailed discussion of the digital minimalism philosophy.

上面的句子摘自2023高考英语新全国卷1阅读理解C的第2段。

请问：part one, part two等表达可以小写首字吗？又如 lesson one, lesson two, book one, book two 等也可以小写首字母吗？