a knife sharpener的用法和样例：
- My pencil is blunt, could you lend me a knife to sharpen it?
- I have a knife to sharpen my pencil with.
- He came running here with a knife held in one hand.
- A knife is one of the simplest of tools.
- His cheek was badly scarred by a knife cut.
- Bank debit card, cancel all the books free of charge services, credit card charges scrape of a knife sharpening, bank credit SMS charges began to notice.