One day a doctor went to a store and bought a pair of shoes. Before he left the shoes counter, he asked the salesgirl: " How long will this pair of shoes last?" 壹天，壹位醫生到鞋店買了雙鞋。他在離開櫃臺之前，問售貨員：“這雙鞋能穿多長時間？”
"It depends. If you don t use it, the shoes will never wear out."“看情況而定。如果您不穿它，那它們永遠也不會壞。”
Several days later the salesgirl fell ill and went to a hospital. And the happened to be the customer she served. After the girl got the prescription from the doctor, she asked: "How soon will I get better with the medicine?"幾天後，這位售貨員病了，去醫院看病。這位醫生碰巧是那位顧客。 當售貨員拿了處方後，問道：“吃了這藥，我的病多長時間才能好呀？”
"It depends. " The doctor answered, "If you don t use it, you will never get better. “看情況而定。”醫生說，“如果妳不吃藥，妳的病永遠也好不了。”