to begin with 是一个习语，可以放在句首、句末或者句中，不能接宾语。具体用法如下（注意标点符号）：

       to begin with  a) spoken used to introduce the first and most important point you want to make 【口】首先 [ 用于引出首先想说的、最重要的内容 ]：Well ,  to begin with , he shouldn't even have been driving my car. 好吧，首先他本来就不应该开我的车。b) used to say that something was already in a particular condition before something else happened 原先，本来：I didn't break it ! It was like that  to begin with . 不是我弄坏的！它原来就是这样的。 c) during the first part of a process or activity 起初，开始的时候：The kids helped me  to begin with , but they soon got bored. 开始时孩子们都来帮忙，但他们很快就厌烦了。（摘自《朗文当代高级英语辞典》第6版，英英英汉双解版p.204）