This poor child, to whom her mother never said 'You are my daughter' except to order her to keep her now that she was old just as she had been kept when she was young, this wretched creature was called Louise and, in obedience to her mother, she sold herself without inclination or passion or pleasure, rather as she might have followed an honest trade had it ever entered anyone's head to teach her one.

1. This poor child, to whom her mother never said 'You are my daughter' except to order her to keep her now that she was old just as she had been kept when she was young，是一个“左偏置结构”，里面包含一个非限制定语从句：to whom her mother never said 'You are my daughter' except to order her to keep her now that she was old just as she had been kept when she was young

在这个定语从句中，now that she was old 是原因状语从句，修饰 to order her（因上了年纪所以命令女儿抚养她），just as she had been kept when she was young 是方式状语从句，修饰 keep her（以这样的方式抚养主语本人）。这里，两个状语从句分别修饰自己的谓语动词。

2.  this wretched creature 和 This poor child 是同位关系。偏置结构就是，用不同的说法重复句子的主语，跟同位语差不多。

3.  and 前后是两个并列分句。

4. 分析第二个并列分句：and in obedience to her mother, she sold herself without inclination or passion or pleasure, rather as she might have followed an honest trade had it ever entered anyone's head to teach her one.

rather 是个强调副词，以加强后面 as 方式状语从句的语气，意为“简直就是”。这个方式状语从句 as she might have followed an honest trade had it ever entered anyone's head to teach her one. 中，又包含着一个条件句had it ever entered anyone's head to teach her one。而且，这个方式状语的主从句，都用了虚拟语气。

第二分句的意思是：为了顺从母亲，她毫无兴趣、毫无激情、毫无乐趣地出卖自己，简直就像她可能会从事正经的职业那样，如果有人想到教她做这样的职业的话。

【注】原翻译没有把这个方式状语呈现出来。