I will have written this letter.

问题描述:

I will have written this letter.
改成被动语态是不是这样:This letter will has been written by me.原句的时态主要靠have 还是be来体现 即改被动后应该变成had 还是been
有什么规则吗

应该是 This letter will have been written by me.
原句的时态靠have来体现,被动式中用have been