关于sit-in student

关于sit-in student sit in,sit on,sit at,sit down的区别 sit in a boat we sit lines in children sit -----in china sit in the sun I would sit squirming in my sit sit in a chair sit on区别 sit in 与sit on 的区别? sit on与sit in的区别 sit on ,sit at ,sit in的区别 sit in、sit off、sit back各是什么意思