It is a wild night indoors, and what must it be in a stone hut upon the moor. What passion of hatred can it be which leads a man to lurk in such a place at such a time! And what deep and earnest purpose can he have which calls for such a trial! There, in that hut upon the moor, seems to lie the very centre of that problem which has vexed me so sorely. I swear that another day shall not have passed before I have done all that man can do to reach the heart of the mystery.
1）为何是must it be, can it be, can he have 如此的语序 ? 为何不是it must be, it can be, he can have 如此的语序呢？ 麻烦老师解析一下。
2) what must it be, What passion of hatred can it be, And what deep and earnest purpose can he have 这3个结构中的what都是what的哪种使用方法和含义呢？ 3个使用方法都是一样的吗？
3）And what deep and earnest purpose can he have which calls for such a trial： which的先行词是否整个“And what deep and earnest purpose” 呢？
4）I have done all that man can do 这里是否少了一个that, 即I have done all that that man can do = I have done what that man can do ?
It is a wild night indoors, and what must it be in a stone hut upon the moor. What passion of hatred can it be which leads a man to lurk in such a place at such a time! And what deep and earnest purpose can he have which calls for such a trial!
这三个what开头的句子都是疑问句，所以句子使用倒装结构。
说话人可以用问句的形式表示一种感情色彩，比如气愤、惊讶、很难置信等。比如一个父母回家发现儿子把一个贵重物品损毁了，他可能说：What have you done!
又如，有人半夜敲门，你了解是Tom，由于没别的人在这时会敲你的门。你会对老婆说，Who can it be . (除去汤姆，还会有哪个呢。）
What man can it be who has such a big house! 什么人才会有这么大的房屋啊！
How should I know! 我如何会了解！
这种问句是修辞性问句的范畴。你的句子中的问句就是这种问句。一般无须听话人回答，而是表示一种感情色彩，所以句子可以用感叹号或者句号。
