What is the subject of "What should I do?"

The answer to the question is "I should do [what]", where I is clearly the subject.

Is that the right answer? I keep thinking the answer should be "What", if only because it's first.

Solution 1:

"I" is the subject of the sentence. This is being confused by two factors. First, as part of general question asking-syntax, English moves an auxilliary verb to the start of the sentence (or adds "do" if one isn't already present). Question words are also moved to the start of the sentence regardless of their part of speech. So "what" is the object of the verb "do", even though "what" occurs at the start of the sentence and "do" appears at the end.