1. Before + 名词/代词/动词的-ing形式，表示在某事之前发生的动作或状态。
例如：
Before leaving home, she always checks that she has her keys.
走之前，她总是检查她有没有带钥匙。
He had never seen the sea before.
他以前从没有见过大海。
2. Before + 句子，表示在某事发生之前的情况。
例如：
I need to finish this report before I leave for the weekend.
我需要在周末离开之前完成这份报告。
She wanted to talk to her boss before he left the office.
她想在老板离开办公室之前和他谈谈。
3. Before + 现在完成时，表示完成某事前已经做了某个动作。
例如：
I have never seen such a beautiful sunset before.
我以前从未看过如此美丽的日落。
She has already finished her work before her colleagues arrived.
她在同事到达前已经完成了工作。
4. Before + 过去完成时，表示完成某事以前已经做了某个动作。
例如：
He had studied hard before he took the exam.
他参加考试前已经努力学习了。
They had already eaten dinner before they went to the cinema.
对于这个问题，我还需要更多的上下文和信息才能回答。您可以给我更多的细节和背景吗？需要帮助的是什么？谢谢！