1. What body shape is underwear based on to design on?

2. What body shape is underwear based on to design ?

——这两个都是错句。不要继续研究了，就按照我说的两个句子即可。

改正办法为：

1. What body shape is underwear designed on?

结构：be designed on...（内衣）根据...而设计。

2. What body shape is the design of underwear based on?

结构：be based on...（内衣设计）以...为基础。

这个问题，我上次给你解答过了。你用的是 What the kind of people 作主语，我改为：What body shape 作主语。