1. When is the report due?

Question

It is due on Monday.

2. When is the book due?
It is due on March 10th.

(Are the short dialogues correct?)

3. What are you saying?
4. What are you speaking?
5. What are you talking about?
(Are the three commonly used and grammatical?)

Answer 1

1 and 2 are correct.

3 and 5 are correct and commonly used.