前天的用法和樣例：
例句
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我希望星期五之前天氣會好轉。
I hope the weather will improve before Friday. -
前天我見過他，但後來再沒見過他。
I see him the day before yesterday, but have not see him since. -
今天要是星期三，前天就是星期一。
If today is Wednesday, the day before yesterday was Monday. -
我前天去購物了。
I went shopping the day before yesterday.
