将否定句改为被动语态，主要需要关注be动词和否定词的位置。以下是一些具体的步骤和示例：

一般现在时态和一般过去时态的否定句

否定词（如not）直接加在be动词后面。

例如：

I do not like this book. [改为被动语态] This book is not liked by me.

They did not finish the work. [改为被动语态] The work was not finished by them.

一般将来时态和现在完成时态的否定句

否定词（如not）加在助动词（do/does/did）后面，然后是主语和动词原形。

例如：

We will not attend the meeting. [改为被动语态] The meeting will not be attended by us.

They have not completed the project. [改为被动语态] The project has not been completed by them.

疑问句的情况

将助动词“was/were”提前至句首，其余部分与陈述句相同。

例如：

Was he writing a letter？ [改为被动语态] Was a letter being written by him？

通过以上步骤，可以轻松地将否定句改为被动语态。总结起来就是：

一般现在时和一般过去时：否定词 + be动词

一般将来时和现在完成时：助动词 + not + be动词

疑问句：助动词 + was/were + 主语 + 动词原形（改为被动语态时，助动词提前）