Answer:
What is something yet nothing, but if you fill it up it will disappear?
I shave several times a day, yet I still have a beard. Who am I?
What comes down but never back goes up?
When it's dirty this should never be aired in public.
What is it that you ought to keep after you have given it to someone else?
I repeat only the last word you say. The more I repeat, the softer I got. I cannot be seen but can be heard. What am I?