could you please comment and explain more the gramaticul function of each of the sentence
What caused him to change his mind?

I think: What is question word subject of the verb cause, and him is the object (please explain more). But what about (to change his mind.

Question

could you please comment and explain more the gramaticul function of each of the sentence
What caused him to change his mind?

I think: What is question word subject of the verb cause, and him is the object (please explain more). But what about (to change his mind.

Answer

'Him' is actually the indirect object. 'To change his mind' is an infinitive that functions as a noun and is the direct object of the sentence.

http://www.dailygrammar.com/Lesson-220-Noun-Infinitives.htm

Answer

"What caused him to change his mind?"

"What caused (it)?" - What happened to make him do "it"? What is the reason behind "it"?

("it" refers to him changing his mind.)

"him" is the person you talk about. He "changed his mind" - for example, if he had an opinion earlier and something then happened (which is what you are asking because you want to know what exactly that was) and that "caused" him to "change his mind".

Answer

xxx cause somebody to do something