what you had done added to our difficulties.帮忙分析这个句子为什么add后要加ed
问题描述：
what you had done added to our difficulties.帮忙分析这个句子
为什么add后要加ed
答
what you had done主语 added to 谓语 our difficulties宾语
add 作谓语动词 ,加ed 是过去式.