合并句子 She stayed there.She wanted to see what would happen to the soldiers.

两个句子的意思是：她留在那里。她想看士兵们会发生什么事。
这两个句子的关系是后面一个句子是前面一个句子的目的。她呆在那里是想看士兵们会发生什么事。因此，可以用动词不定式做目的状语。
She stayed there to see what would happen to the soldiers.

She stayed there to see what would happen to the soldiers.
She stayed there and wanted to see what would happen to the soldiers.
She stayed there because she wanted to see what would happen to the soldiers.
She stayed there, wanting to see what would happen to the soldiers.

She stayed there to see what would happen to the soldiers.

She stayed there that wanted to see what would happen to the soldiers