问题描述: i need to buy a book 改为否定句i need to buy a book改为否定句 1个回答 分类:英语 2014-10-04 问题解答: 我来补答 i don't need to buy a book 再问: need 在否定句中不是情态动词吗?为啥还要跟to 再答: need后跟do是情态动词,跟to do是实义动词再问: I needn’t buy a book不对吗? 再答: need只有做情态动词才能直接加not 再答: need to do中的need只能是实义动词 展开全文阅读