look forward to为什么前面要加be动词

look forward to为什么前面要加be动词 look forward to应该接什么?为什么 急look forward to与Look forward look forward to等于 Look forward to造句 look forward to 造句 look forward to look forward to,wonder look forward to your look forward to doing. look forward to look up/look forward to look forward to your letter 为什么不用expect I look forward to seeing you.为什么see加ing LOOK forward TO 还是LOOK FORWARDS TO look forward to和look up、look out分别为什么意思抓紧!急!提前谢谢了 look forward to和look forward to doing的区别 they look forward to watching the match.watching为什么要加ing?是look forward to 的固定用法吗?