a 'for sale' sign的用法和样例：
- "For sale," he called out, quoting a sign.
- This is a showpiece, not for sale.
- A rare collection of china will be up for sale next month.
- Last week my wife and I arranged to see a house that was for sale.
- Something bought or for sale; a purchase.
- Look in the small ads to if anyone have a computer for sale.