1.As it is, without any addition of mine, they will each have about three thousand pounds on their mother's death--a very comfortable fortune for any young woman.

【难句解析】as it is 意思是“事实上”；on their mother's death意思是“她们的母亲一死”；

【句子翻译】其实，即便没有我这份补贴，她们的母亲一死，她们每人都能得到三干多镑，对于一个年轻女子来说，这是一笔相当不错的财产啦。

2.That is very true, and, therefore, I do not know whether, upon the whole, it would not be more advisable to do something for their mother while she lives, rather than for them--something of the annuity kind I mean.

【难句解析】upon the whole原因是“从整体上看”；be advisable to do sth.意思是“做某事更可取”；

【句子翻译】的确如此。所以我在琢磨，整个来看，趁她们母亲活着的时候，给她点补贴，这是不是比给她们更可取呢？我的意思是给她点年金什么的。这个办法产生的良好效果。