整个句子中,it是形式主语,后面的to have more money to take care of,more begging letters to read,and to be cut off from those delicious Alnaschar dreams in which the poor man,sitting down to consider what he will do in the always possible event of some unknown relative leaving him a fortune,forgets his own situation of being poor?是真正主语.真正主语中包含两个动词不定式短语to have more money to take care of,more begging letters to read,和 to be cut off from those delicious Alnaschar dreams in which the poor man,sitting down to consider what he will do in the always possible event of some unknown relative leaving him a fortune,forgets his own situation of being poor.第一个不定式短语 to have more money to take care of,more begging letters to read是主动表被动结构,就像我们常说的句子：I have something important to do.一样,也是主动表被动.第二个不定式短语中包含一个定语从句,先行词是 dreams,后面的in which the poor man,sitting down to consider what he will do in the always possible event of some unknown relative leaving him a fortune,做定语修饰dreams.在定语从句中,有一个现在分词短语sitting down to consider what he will do in the always possible event of some unknown relative leaving him a fortune,做伴随状语,在这个分词短语中包含一个宾语从句 what he will do in the always possible event of some unknown relative leaving him a fortune.