先前的英文：
before
previously

参考例句：

antecedent debt
先前的债项

The eyewitness contradicted earlier testimony
目击者否认了先前的证词。

A cassette containing blank or prerecorded videotape.
录像带空白或者先前录制好的盒式录像带。

He spoke with such earnestness and lucidity that he made Tang Yun-shan feel rather small and regret his suspicions
他这一番话，又恳切，又明晰，倒使得唐云山感觉到自己先前的猜度——以为中间有几分奥妙，未免太不光明正大了。

It's hurting worse than before.
比先前痛得更厉害了。

He recalled his earlier instructions.
他撤销了先前的指令。

This doesn't consist with what you told me earlier.
这和你先前告诉我的不符合。

Early money is like yeast.
先前的钱就跟泡沫一样。

It was black, cold, and lifeless as before.
它还是先前一样黑暗，冷清，死气沉沉。

We would like three Blue ones in addition to the ones we previously ordered.
"除了先前定购的,我们还要三个蓝色的。"

before是什么意思：
prep. 在…之前；优于，先于；当面
conj. 在…之前
adv. 先前，从前

Rain before seven;fine before eleven
雨过天晴

They corned their horses before the journey.
他们在启程前用玉米喂马。

The army was arrayed before the commander.
部队在指挥官前列好阵势。

see before you go
三思而行

Bind the sack before it be full
做事应适可而止

previously是什么意思：
adv. 预先；以前

The land previously cultivated returned to forest.
以前开垦过的那片土地现在又成了森林了。

Many of the previously detected systems are “full”.
许多已被检测到的星系都是“满”的。

You are a little previous in learning English.
你在学习英语上有点过急。

He was judging by previous dinners.
他是照从前吃过的晚饭来猜测的。

the indiscriminate policies of the previous administration.
前任内阁令人困惑的政策