1. But when the emotion that leads to stiffening the lip is more intense, and involves strong muscle tension, facial feedback may heighten emotional response. 但是当导致嘴唇僵硬的情绪变得更加强烈，并导致肌肉强烈绷紧时，面部表情反应就可能会增强情绪反应。
2. A litre of teacan contain up to 9mg of fluoride, which in excess can cause skeletal fluorosis, reducing bone quality and causing pain and stiffening of the ligaments. 一升茶树含有高达9毫克的氟化物，过量会导致氟骨症，降低骨骼质量，导致疼痛和韧带僵硬。
3. The storm was stiffening then. 那会儿，风暴变得越来越猛烈。
4. And stiffening the backbones of the sea! 让海的脊骨变硬！
5. The White House, in turn, may be stiffening its strategy. 对于白宫来说，其可能加强其战略。
