如何改为否定句（英语)

一般现在时：在be(am,is,are)动词后加not,即（am not,aren't,isn't).一般过去时：在were,was后加not.即weren't,wasn't.其他时态的一般都是在谓语后加not。还有就是some改any（如果是表示想得到肯定回答，不必改）,something改anything。

一般来说，英语中否定词都放在最前。比如将I think I need a pen.改为否定句时，不会说I think I don't need a pen. 而是说I don't think I need a pen.

有have，has，be（am，is，are，was，were）在后面加not
没有在谓语动词前加don't，doesn't（一般现在时单三），didn't（过去时）
有情态动词（can,could,shall,should）或will，would也在它们后加not
够简练了吧`

如:I
am
a
student.
改为否定只要在be动词am后加not就好
而he
is
a
student，则在is后加not，另外is
not
可以改成isn't
you
are
a
student,则在are后加not，另外are
not
可以改为aren't

在系动词BE 后面加not,比如 he is a good student变为he is not a good student.
在实义动词前面加助动词和not he studies well变为 he doesn't study well