at first

1. 起先
   At first I didn't know what had happened.

   起先我不知道发生了什么事。

first and foremost

1. 首要的是
   He's written many different kinds of things, but he's first and foremost a novelist.

   他写过许多不同性质的东西，但他首先是位小说家。

first and last

1. 彻头彻尾
   He is an artist first and last.

   他是个纯粹的艺术家。

first of all

1. 第一，首先
   He is a great soldier first of all.

   他首先是位伟大的军人。

first or last

1. 迟早
   He will marry the girl first or last.

   他迟早会娶那姑娘的。

from first to last

1. 自始至终
   He remained silent from first to last.

   他始终缄口不言。

from the (very) first

1. 从一开始
   She knew she was in love with Henry, from the very first.

   从一开始她就知道自己爱上了亨利。

• at first
  at the beginning.
• first and foremost
  more than anything else.
• first and last
  fundamentally.
• first of all
  before doing anything else.
  ▸most importantly.
• first off
  informal as a first point; firstly.
• first past the post
  winning a race by being the first to reach the finishing line.
  ▸Brit. denoting an electoral system in which a candidate or party is selected by achievement of a simple majority.
• first thing
  early in the morning; before anything else.
• first up
  informal first of all.
• in the first place
  as the first consideration or point.
  ▸to begin with.
• of the first order (or magnitude)
  excellent or considerable of its kind.