英语中变成否定句有两类。

一，祈使句的肯定句变成否定句。直接在动词原形前面加don't。例如:Go out. ->Don't go out.二，陈述句变成否定句。1.在am/is/are/was/were后＋not。例如:He is old.->He is not old.2.在情态动词后＋not。例如:He can swim.->He can not swim.3..在助动词动词后＋not。例如:I will go tomorrow.->I will not go tomorrow.4.借助助动词，在其后＋not。一般现在时态借助do/does,一般过去时态借助助动词did＋not，借助does/did之后动词还原。动词是原形的借助do,动词＋s的，借助does,过去式的，借助did.例如:I know.->I don't know. He knows.->He doesn't know. They knew.->They didn't know.5.其他变化。some -> any ,some 合成词-> any 合成词，too 变either， and 变or。