How to Use “以前(yǐqián)” And “以后(yǐhòu)” in Chinese

Situation 1:
“以前(yǐqián)” can be used after a time word to express before or ago. The structure is “time + 以前(yǐqián).”

Examples:
Wǒ bā diǎn yǐqián dào gōngsī.
我 八 点 以前 到 公司。

Situation 2:
“以前(yǐqián)” and “以后(yǐhòu)” can also be used after a certain action to indicate a period of time. The basic structure is “action + 以前(yǐqián)” and “action + 以后(yǐhòu).”
The structure “action + 以前(yǐqián)” indicates the period of time before the action or event.

Examples
Shàngbān yǐqián, wǒ yào chī zǎo fàn.
上班 以前，我 要 吃 早 饭 。