Answer:
When you buy me I am costly, but the only use I have is hanging only. What am I?
The dirtier I get, the whiter I am. What am I?
I am so delicate that even mentioning me breaks me. What am I?
You throw me out when you use me and take me in when you are done.
Curtail me thrice I am a youth; behead me once a snake; complete I'm often used in truth when certain steps you'd take.
Runs over fields and woods all day. Under the bed at night sits not alone, With long tongue hanging out, Resting at your feet until we go for a walk