1. That afternoon aboard the train, the cousins settled down in their seats. (P34)
【归纳】 settle down 平静下来，定居，适应起来，专心于。
【延伸】 settle down to专心致力于，逐渐习惯于；settle in搬进新居，安顿下来；settle on栖息，选定，决定，停留；settle sth on sb将某物转让给某人；settle for sth 勉强认可某事；settle oneself in one’s seat在座位上坐定。
【易错点】 settle down, settle down to：这组短语结构相似，但含义和用法不同。settle down作“安稳地坐下，安居下来，安静下来”解，后接介词短语（表地点），可接不定式（表目的）；settle down to意思是“安下心来做某事，认认真真做某事”，其中to为介词。如：
She didn’t start the lesson until the pupils settled down.
The constant interruptions stopped him settling down to his work.
She settled down in a sofa to read her book.
