He hasn't expanded in the development section.
他在展开部并没有完全展开。
Development section
原声例句
聆听音乐（视频版）
聆听音乐（视频版）
There's a lot going on in the development section.
在展开部中许多元素都在同时进行。
聆听音乐（视频版）
And it's kind of fun the way Mozart starts the development section here.
莫扎特把展开部的开头写得很有意思。
聆听音乐（视频版）
We're going to proceed here and we're going to go in to the development section.
我们继续开始进行展开部。
英语百科
Musical development
![Development in Haydn's sonata in G major, Hob. XVI: G1, I, mm. 29-53 Play .[1]](/uploads/202501/08/Development_Haydn's_Sonata_in_G_Major4253.png)
In classical music, musical development is a process by which a musical idea is communicated in the course of a composition. It refers to the transformation and restatement of initial material, and is often contrasted with musical variation, which is a slightly different means to the same end. Development is carried out upon portions of material treated in many different presentations and combinations at a time, while variation depends upon one type of presentation at a time.