问题描述： 现在进行时怎样变否定 1个回答 分类：英语 2014-10-28 问题解答： 我来补答 现在进行时的结构是:动词BE(AM/ IS / ARE )+动词ING 形式,所以其的否定形式是直接在BE后加NOT,如:He is doing his homework -> He isn't doing his homework. 展开全文阅读
