Answer:
What cannot talk but will always reply when spoken to?
What occurs four times in every week, twice in every month, only once in a year but never in a day?
Big as a saucepan, deep as a cup, Even a river can't fill it up. What is it
What has roots that nobody sees, and is taller than trees. Up, up it goes, and yet it never grows.
There is an ancient invention still used in some parts of the world today that allows people to see through walls. What is it?
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.