Answer:
Brown I am and much admired. Many horses have I tried. Tire a horse and worry a man, tell me this riddle if you can. What am I?
Six legs two heads two hands one long nose. Yet I use only four legs Wherever I go.
I help you carry your books.
When the clock has no angle, I will own yesterday, tomorrow and tonight. What am I?
I hold two meanings. With one I may be broken, with the other I hold on. What am I?
No matter how little or how much you use me, you change me every month.