had written,was written,is written,have written有什么差别?

had written 过去曾经写过，He had written a book two years ago.
was written 被…写，由…创作（过去，已经写完）。 This novel was written by Marks.
is written 被…写，由…创作（现在）。 This letter is written by Lucy.
have written 已经写完 He has written 3 book since 1997.

had written, have written 完成时，前者是过去完成时，后者是一般现在完成时
is written, was written 前者是一般现在时的被动语态，后者是一般过去时的被动语态
以上涉及到一个时态的问题

1.had written是过去完成时态.发生在过去的过去.比如说：“我在他写这类文章之前就已经写过了”.他的文章已经写好了,而我的比他更早写好.就应该是“I had written this kind of essay before he wrote it."2.was wri...

had written,过去完成时
was written,过去被动
is written,现在被动
have written，现在完成时