1.first用作形容词一般修饰单数名词,修饰有few或数词修饰的复数名词时是把复数名词看作一个整体。first与基数词连用时,一般置于基数词前,但first引起的固定词组则应置于基数词之后。
2.first作“一点也不”解时,常用于否定句中。

用作定语
▲～+n.
Do you know when the first artificial satellite of America was launched?你知道美国的第一颗人造卫星是什么时候发射的吗?
It was the first time I had ever been in a plane.那是我第一次乘坐飞机。
Freshmen have military training for a month from the beginning of the first term.新生在第一学期一开始就有为期一个月的军训。
As for your hope of winning the first prize,I don't know about that.至于说到你希望获头奖,对此我没有多大把握。
He is the first actor of China.他是中国第一流的演员。
It is of the first importance.此事头等重要。
The first duty of the state is to ensure that law and order prevail.政府的首要职责是确保治安高于一切。
He didn't feel glad for the first few days.在最初几天里他并未感到高兴。
For tomorrow I want you to do the first six problems.我要你明天做前六个问题。
The two men over there are his two first cousins.在那里的两个人是他的嫡亲兄弟。
I haven't the first idea of what you mean.我一点也不懂你的意思。
用作表语
▲S+be+～
She is first in her class.她是班上的第一名。

［同义词］ adv. foremost, primarily adj. basic, chief, earliest, primary
［反义词］ adv.  &  adj. last
［词源］＜古英语fyrest(最初的,第一流的)

first and foremost
首要的 more than anything else
He was a singer, but first and foremost a scholar.他是个歌手,但他主要是一位学者。

first and last
考虑到一切因素; 完全地 taking everything into account; completely
First and last, it is important to know oneself.总而言之,人要有自知之明。

first of all
首先before doing anything else
First of all,you should know what profession suits you.首先,你该知道什么职业适合你。

first or last
迟早sooner or later
I know that this would happen, first or last.我知道这事迟早会发生。

First, let me deal with the most important difficulty.首先,让我来处理最为重要的问题。
Modern music was first developed in Italy.现代音乐最初是在意大利发展起来的。
When we first lived here there were no buses.我们最初住在这里的时候,没有公共汽车。
All mothers fear for their children when they first leave home.孩子初次出门,母亲总要为之担心。
I'll never allow you to do that; I'll die first!我绝不允许你做那种事,我宁愿死!

first of all, above all, in the first place
参见above条。

在表示逐项说明一系列的事实或情况的第一项时,可用first,也可用firstly。例如:
First(ly), she has to look after the children; second(ly), she has to cook meals; third(ly), she has to clean the house.第一,她必须照看小孩; 第二,她必须做饭; 第三,她必须打扫房间。

first作为序数词用时,意为“第一(个、批),头一〔几〕个”,常和定冠词连用。

at first
起初,当初 at or in the beginning
At first, he was against our arrangement, but I managed to argue him round.起初,他反对我们的安排,但我设法使他改变了看法。

from the first
从头,从一开始 from the beginning
It was evident from the first that he never intended to carry out his promise.他不打算履行诺言从一开始就是很明显的。

I'm the first in our village to go to university.我是我们村第一个上大学的。
The first is better than the second.第一个比第二个好。
This second event was contemporary with the first.第二个事件和第一个事件发生在同一时代。