Question

求教英语高手！

He grew so attached to the gas that he drewon it three or four times a day. Eventually, in1829, it is thought to have killed him. 最后一句话是虚拟语气还是被动语态，或是其他什么？这句话是什么意思？have killed him 是什么语法？

Answer 1

have done 是完成时态，it is thought to do 意思是有人认为......，此处it 作为形式主语，真正的主语是to do 之后的内容
be said/be supposed/be believed/be thought/be known/be reported+to do (要做)/to be doing正在做/ to have done做完了
拓展：
it is hoped that...人们希望
it is thought that...有人认为
it is ordered that... 已下令
it is supposed that...据推测
it is well known that...众所周知
it is pointed out that... 需要指出的是
it must be admitted that...必须承认的是
注意：此种句型it为形式主语，真正主语为that引导的从句，且that 不可省略

追问

这句话是什么意思，能翻译下吗

Answer 2

这里我大致翻译这段文字的意思，希望有助理解，然后你会明白句子结构的：
我坐在这里，现在是2003年初，我面前是几页来自美国自然历史博物馆Ian Tatterwall
的手写审阅稿。在审阅稿中，Ian Tatterwall热情地鼓励我，同时也委婉地指出其中的问题，他特别指出，Periguetix不是葡萄酒产区，我用斜体字来表示生物种属以上的分类有创意但不正规，以及我不断地拼错Olorgesailile（这地方我刚去过），等等问题。Ian Tatterwall 以同样的方式既鼓励又委婉的方式审阅了覆盖他的专业领域早期人类的两章。
分析：that Periguetix is not a wine-producing region that it is inventive but a touch unorthodox of me to italicize taxonomic divisions above the level of genus and species,这句话中间应该有一个逗号，如下：that Periguetix is not a wine-producing region， that it is inventive but a touch unorthodox of me to italicize taxonomic divisions above the level of genus and species,
句子主干是：I have pages bearing notes pointing out that...，that... ， that...，（意思：我有几页稿纸，其上有审阅意见，意见指出如此，如此，如此）

其中bearing notes pointing out that...，that... ， that...，是非谓语短语作定语修饰pages；另一个非谓语短语pointing out that...，that... ， that...，也作定语修饰notes。