Could you explain as to where you have been all this while?

Mr. TomCould you explain as to where you have been all this while?

No. It's not natural. It's wrong. You can fix it like this:

Could you explain where you have been all this while?

Or like this:

Could you [give / offer] an explanation as to where you have been all this while?

CJ

Thanks, CJ.

Does it mean that "noun + as to" works in most situation but "verb + as to" doesn't?

Do these work?

He asked several questions as to our repeated failure over that small issue.
He questioned why we had failed repeatedly over that small issue.

Tom

Mr. TomHe asked several questions as to our repeated failure over that small issue.

This one is borderline. It's understandable, but not quite right because we'd say "about" instead of "as to" in this case.

Mr. TomHe questioned why we had failed repeatedly over that small issue.

Good.

Mr. Tom"noun +

Examples of "as to" (regarding; about). Do not confuse with "so as to", "so ... as to", or "such ... as to".

Probably most uses of "as to" are followed by an indirect question, i.e., a clause that starts with a question word (whether, why, how, how much, what, which, when, where).

Debate is raging as to whether ... or ....
There is some doubt as to whether the informa