Would you mind if I come up for a visit soon?
I wonder if her sister were named Sue.
Both if clauses are placed in the object slot.
Can they function as nominal?
I refrain from using such terms as ‘if clause’ and ‘that clause’ for the simple reason that they are ambiguous. And this sentence shows why.
Like a ‘that clause,’ which can be both a relative and noun clause, an ‘if clause’ can function both adverbally and nominally.
Generally, ‘whether’ is used instead of ‘if’ when it is a nominal clause. But this is not to say that this is incorrect.
And, to my knowledge, this is definitely a noun clause, the direct object of the verb to wonder.
Many would make the mistake and state that it is adverbial, because a)it looks like it modifies the verb ‘wonder’ b)it is an ‘if clause’ which most commonly is an adverbial clause.
