stiffen
- vi. 变硬；变猛烈；变粘
- vt. 使变硬；使粘稠
考试真题
- The advantages, not surprisingly, were greater for African Americans, who are more likely to develop high blood pressure than other ethnic groups, and for the elderly, since blood vessels stiffen with age, which can lead to higher blood pressure.
出自-2013年6月阅读原文