underjaw

例句：

1. 1. The underjaw of thefish was visible through the water.
   鱼的下颌在水下可见。
2. 2. The dentist had toremove the underjaw for the patient's mouth.
   牙医不得不为病人的嘴巴取出下颌。
3. 3. The underjawis a crucial part of the animal's digestive system.
   下颌是动物消化系统的关键部分。