jointing at inside corner

例句：

1. 1. The car's engine has a lot of joinings that need to be tightened.
   这辆车的引擎有很多接缝，需要拧紧。
2. 2. The two pieces of wood fit together perfectly at the joint.
   两块木头在接缝处完美地吻合在一起。
3. 3. The engineer used special tools to join the metal parts together.
   工程师使用特殊的工具将金属部件连接在一起。