1、first of all:第一;首先
First of all we must identify the problem areas.
首先我们必须找出问题所在。
2、at first:最初;起初;开始时
At first I couldn't believe it。 I thought it was a wind-up by one of my mates.
一开始我不相信,以为是哪个同伴在故意逗我。
3、at the beginning of:在…初;首先
The wedding will be at the beginning of March.
婚礼定于三月初举行。
4、to start with:(事情、过程等)开始时,一开始;首先;第一
To start with, the pressure on her was very heavy, but it's eased off a bit now .
一开始,她的压力很大,但现在已经好些了。
5、to begin with:刚开始;首先;最初;第一
To begin with he was Prince Charming.
首先,他是一个白马王子。