I have not been to Beijing since graduating from tsing hua univer_英语解答

I have not been to Beijing since graduating from tsing hua university
为什么要用'graduating ing形式

人气：103 ℃　时间：2020-03-25 03:52:29

解答

since 在这里没接句子,那么就是介词,介词后要接动名词（v-ing) 作宾语