坐下英语单词是sit down。sit down的例句：Sit down and be quiet in front of your elders and betters（在长辈和上级面前要老老实实地坐着）。

sit down的例句：Hughes beckoned him to sit down on a sofa（休斯示意他坐在沙发上）；They sought out a shady spot where they might sit down and rest（他们找到一块阴凉地方可以坐下休息）。