He fell down and hurt his knee.

他摔倒了，伤了膝盖。

同一单元的其他句子

• What's the matter with you?你怎么了？
• I have a headache and a fever.我头疼并且发烧。
• You should drink more hot water.你应该多喝热水。
• He has a sore throat and can't talk.他喉咙痛，不能说话。
• She cut her finger while cooking.她做饭时切到了手指。