问题描述: but my friends and i think it must be teenagers having fun为什么用having 1个回答 分类:英语 2014-11-26 问题解答: 我来补答 意思是我和朋友们认为一定是有乐趣的青少年,这里having fun 做定语修饰teenagers,可以变态理解为my friends and i think it must be having fun teenagers,所以be动词+doing.所以. 展开全文阅读