Why to use the て-form in questions?


Anybody around here knows why it is used the て-form in 覚えてないのかい instead of
覚えないのかい in the next sentence?

僕はさっきもう君にすっかり話したじゃないか。 それとも、覚えてないのかい？ I've already seen this before in other
question sentences So..., What I want to know is why it is use the て-form in
question sentences? I mean.... If I use both of them (覚えてないの､ 覚えないの ) the
meaning of the sentence wouldn't be the same?

