grey hairs的用法和樣例：
例句
- Encourage the older patients to play card games or do simple jigsaw puzzles-anything that keeps the grey matter in use.
鼓勵老年病人打牌或做拼板遊戲等事情，只要讓他們動腦子就行。 - The paper analyses the characteristics of the American segmentation of the grey market and its significance in marketing.
評述美國老年市場細分模型的特點及其在營銷上的意義。
