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 written和is written是被动语态.时态不同.“这首歌是他写的” “this song is written by him." “这首歌是他十年前写的”:“this song was written by him 10 years ago.” 3.have written是现在完成时.表示到现在为止 写完.比如.“我现在已经写了3本小说”就是“I have written 3 novels by now."