前天的英文：
the day before yesterday

参考例句：

The day before yesterday I read a piece of news about "Job problem" of the Two Sessions.
前天，我看了一则关于两会就就业问题提出的主题讨论消息。

The darkest hour is nearest dawn
黎明之前天最黑

If today is Friday, the day before yesterday is Wednesday.
假如今天是星期五,前天就是星期三。

They happened to pick up each other in a park the day before yesterday.
他们前天在一个公园里偶然结识。

"If today is Friday, the day before yesterday was Wednesday."
〞假如今天是星期五,前天就是星期三。〞

"My wife was telling me the other day that you and Su-su have had a bit of a tiff."
“前天听佩瑶说起，你和素素中间有了变化？”

Tom was strikingly different the next day--quiet, limp, calm like honey
汤姆的状态显著与前天不同--安静、无力，像蜂蜜一样平静。

day是什么意思：
n. 一天；白昼，白天；工作日；时代，时期

Things go on day by day.
事情逐日进行着。

Day by day the situation is improving.
情况在一天天地好转。

Like this, day after day.
就这样，日复一日。

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。

yesterday是什么意思：
n. 昨天；往昔；过去
adv. 昨天

We went rabbiting yesterday.
昨天我们打兔子去了。

They leveled a field yesterday.
他们昨天平整场地了。

The badass was schooled yesterday.
那个坏蛋昨天受到了教训。