Look farward to与look farward to doing的区别

Look farward to与look farward to doing的区别 look farward to devote oneself to doinglook farward to doing 中的to是什么词性啊?to doing是什么结构啊?可非谓语中没有TO doing这个说法啊～那to doing是做farward的什么成分? 急look forward to与Look forward 急求look forward 与look forward to 的区别 look back on 与 look back to 有什么区别? look up/look forward to look look down 还有look on?和look forward to? look look! look look look look. look look look look look