变否定句就是在助动词后面加上not，怎么初中阶段所学的助动词，有am，is，are，was，were，do，does，did？Have has, had will, can, may must, should, would.could, might在这些词后面加上not，就变成了否定句。
而把这些词提到句子开头，就变成了一般疑问句。
变否定句的口诀是 don't / doesn't + 原形动词 或者 never + 助动词 + 原形动词，例如：
原句：I like pizza.
否定句：I don't like pizza.
原句：He speaks Chinese fluently.
否定句：He doesn't speak Chinese fluently.
原句：They have finished their homework.
否定句：They haven't finished their homework.
变一般疑问句的口诀是 改变句首的语序，并在句尾加问号，例如：
原句：She is a doctor.
一般疑问句：Is she a doctor?
原句：You can swim.
一般疑问句：Can you swim?
原句：They have seen this movie.
一般疑问句：Have they seen this movie?
