这两个动词不定式在句子中做什么成分This was even more exciting to see than the rapids where the water seemed to boil.请问动词不定式to see和to boil在句中做什么成分?

这两个动词不定式在句子中做什么成分
This was even more exciting to see than the rapids where the water seemed to boil.
请问动词不定式to see和to boil在句中做什么成分?

to see作后置定语,与前面的主语this构成逻辑上的动宾关系.
to boil与前面的seemed共同构成谓语部分,不可分割,seem是不及物动词,只能用seem to do

to see做真正主语。前面的this相当于it是形式主语。. to boil做系动词seem后的表语。