Question

What have you "________" to discover?
(a)been able. (b)able. (c)were able (d)had been​

Answer 1

$hello$

What have you been able to discover?

Option A) Been able.

I hope my answer helps you .....✌

Følløw me

Answer 2

What have you been able to discover?

Explanation:

• If a sentence like this arises, we need to check which options we can use and compare with the sentence until we get a clear answer.
• Trying the options we get,

1. What have you been able to discover?
2. What have you able to discover?
3. What have you were able to discover?
4. What have you had been​ to discover?

• As we can see except "been able", others are not suitable.
• Therefore "been able" is the right answer.