1）He often sleeps with these windows ____A open B opening C to open D be opened
这里的open是形容词,表示打开的.with sth.+形容词表示使某物保持某种状态.
2）Can I have this window open at night?
have sth. done, 使某事被做.have sth.+形容词,可以理解为keep sth.+形容词.
3）The editor remarked that the article was well written.
句子是被动语态,文章写得很好,省略了写文章的人.可以加by somebody,指出作者.well为副词修饰动词.written为write的过去分词.