祈使句是对别人说的,暗含了主语(you),习惯上并不说出来.You ,sit down,please! will you? 前面其实是有人(即:"you")的.the students (carrying books) come in first.带书的先进.其实是说,
You(the students carrying books这是"YOU"的同位语),come in first
1. 祈使句为肯定句式，其反意疑问句表示请求时，通常用will you；表示邀请、劝说时，用won’t you。例如：Be sure to write to us, will you?你一定要给我们写信，好吗？Come to have dinner with us this evening, won’t you?今晚来和我们一起吃饭，好吗？2.
