look at doing sth

look at doing sth 请问什么时候用 see sb doing sth 什么时候用 look at sb doing sth 紧急】see sb do/doing sth,watch sb do/doing sth,look at sb do/d 用run around with sb look around 造句 用look at sb doing sth 造句 look forward to (doing )sth look forward to (doing) sth. 为什么look at sth不能用look sth at look at sth.=have a look at sth. look at sth,or watching look at sth 与look的区别. look forward to do/ 还是 doing sth 为什么是 look foward to doing sth?