I've read through the questions and answers below, but still don't understand the following example.
Test question: "I haven't been in France for long?" (ie, I recently arrived and I'm still here; ongoing).
From the lesson it seems the best construction would be: Ne...pas + Présent Indicatif + depuis longtemps (started a short while ago and is still ongoing).
But Kwiziq says the best answer is: Ne...pas + Passé Composé + depuis longtemps (not for a long time / not in ages).
If someone could explain it more clearly, thanks.