look forward to doing中,to是介词?Ving相当于介词?

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 还是LOOK FORWARDS TO look forward to和look forward to doing的区别 look forward to 的用法 look forward to your letter We look forward to,our look forward to的用法? look forward to 的用法 look forward to 的意思