guard bit

例句：

1. 1. The guard bit onthe door was rusted and couldn't be opened.
   门上的护齿生锈了，打不开。
2. 2. He had a guard bit inhis mouth that kept him from speaking outof turn.
   他嘴里有一颗护齿，防止他说话不经大脑。
3. 3. The guardbit was a symbol of protection for thevillagers.
   护齿是村民们保护的象征。