often see sb.do么?如题?In China we often see people dropping litter on streets...这里为什么答案是有ing的?

often see sb.do么?如题?In China we often see people dropping litter on streets...这里为什么答案是有ing的? see sb to do sb often do.是Sb often do sth.还是Sb often doing sth.哪个正确? 关于初二英语语法的问题（often)see sb.do sth.如果人称是单三,do会有时态变化吗? see sb doing 和see sb do区别用法 see sb to do和see sb doing的区别? see sb do与see sb doing区别 see sb.do和see sb.doing 怎样区分? 关于see sb do和see sb doing的例句 see sb doing和see sb do有什么区别 see.sb.do.的do是什么成分? do sb.a favor造句如题 see sb do sth/watch sb do sth (各造一句) see sb doing和see sb do 和see sb done区别 see sb to do sth还是see sb doingsee sb to do sth还是see sb doing sth 英语概念题,求详解如何区分什么时候用see sb doing 什么时候用 see sb do 初中所有的英语句型要有例句如:see sb +do/doing 用所给单词的适当形式完成句子 I often see Jim -------(walk) across the road to wait for the bus.答案为什么是walk,我觉得应该是 see sb.doing sth.或者see sb.to do sth.