Answer:
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?
I am an activity dogs are very good at when a ball is thrown.
I go around in circles, but always straight ahead, never complain, no matter where I am led.
Adored by few, feared and hated by many. Mistress of the entire universal reason, master in the art of numbers. Some may have solved many of my mysteries, but there are still many of them to find. What am I?
One pace to the north. Two paces to the east. Two paces to the south. Two paces to the west. One pace to the north.
No matter how little or how much you use me, you change me every month.