Thank you for suggestion

哼著他的曲 -> 唱著他的歌 -- I hesitated between the two choices. I picked up "哼著他的曲" to add change of the rhythm but "唱著他的歌" is more consistent with the rest of the poem and also sounds excessive repetition. The latter may be a better choice thinking about the overall effect.

那女孩子正在縫補洗漿 -＞ 在縫補洗漿的女孩 --I use the way to rhyme.

Thank you again.