Question

Not only did I serve in the army, but _____ in the navy for a short while too. 1. I also served 2. I will also serve 3. also I was served 4. have also been served

Answer 1

It is a case of Parallelism of Tense. Parallelism means the use of successive verbal constructions in poetry or prose which correspond in grammatical structure, sound, metre, meaning, etc. In the given sentence Parallelism refers to grammatical structure, predominantly the right tense structure.
So the correct option is given below: Not only did I serve in the army, but I also served  in the navy for a short while too.

Answer 2

Solution :-

Not only did I serve in the army, but 'I also served' in the navy for a short while too.

So, the correct option is (1) - 'I also served'.

Thank you very much.