Question

5.
I haven't seen you
(a) for ages
(b) since ages​

Answer 1

Answer:

I have not since age....

Answer 2

Answer:

I haven't seen you for ages.

Explanation:

To fill in the blank we have to figure out the correct preposition.

for - used to show an amount of time

since - used to show the amount of time passed

In this sentence, they are not talking about the amount of time passed but just the amount of time. Hence we have to use 'for'.