问题描述: Mark did not know what he should do to help him.怎样改为同义句 1个回答 分类:英语 2014-09-23 问题解答: 我来补答 Mark did not know how to help him. 再问: 不对呀,填空是Mark did not know ______ _______ ______to help him. 再答: what should do应该可以,因为主语相同,可省略从句中的主语he 展开全文阅读