knee protector

例句：

1. 1. He wore a knee protector to protect his injured knee.
   他戴着膝盖保护器来保护他的受伤膝盖。
2. 2.The player had to wear a knee protector during the game.
   比赛中，这位球员不得不戴上膝盖保护器。
3. 3. The doctor recommended him to wear a knee protector while he recovers from surgery.
   医生建议他在手术恢复期间戴上膝盖保护器。