[Grammar] Is it correct to ask, "What were you afraid?"?

[Mike MC]

Is the following question correct?

Q.: What were you afraid?
A.: We were afraid that we were going to capsize the boat.

 

[tedmc]

No, you need the preposition "of" at the back.

 

[Mike MC]

No, you need the preposition "of" at the back.

Why? As far as I know a that-clause is a noun clause that functions like a noun. Don't we simply use "what" to ask about a noun? Here's another example:

Q.: What do you guess?
A.: I guess that she is thirty.

 

[emsr2d2]

Regardless of what happens with other "What" questions or "that" clauses, there is simply no way to ask your original question without "of". Even though we can use "We were afraid that ..." in the answer, that can't be converted into "What were you afraid that?" or your shorter version. There is only one grammatical question there:

What were you afraid of? (You might hear people of a much older generation use "Of what were you afraid?")

In the response, what follows "afraid" can differ:

We were afraid of the dark.
We were afraid [that] he would find us.
We were afraid of losing.
We were afraid [that] it wouldn't be successful.