Question

analyse the following sentence. -I am eagerly waiting for the day when I shall be eligible for a driving licence.

Answer 1

This sentence is grammatically correct. it simply means the writer is looking forward to the day he or she will be able to  obtain a driving licence. probably he is below the age mark. Also it would sound better if the writer wrote will instead of shall.

Answer 2

Here in the above sentence,

The letter I will be the subject of the sentence.

Eagerly is the adverb found in the sentence

For is the preposition used here.

We can easily say, the above sentence is the declarative sentence. Because the subject is used first and clearly mentioned the interest in making something.