Before a specific time with "yiqian"

As well as talking about the past in general, you can use 以前 (yǐqián) to talk about things that happened before a specific time.

早上十点 以前，公司没人。 Shí diǎn yǐqián, wǒ zài jiā. I will be at home before ten o'clock.
三年 以前，我来到了上海。 Sān nián yǐqián, wǒ lái dào le Shànghǎi. Three years ago I came to Shanghai.
来中国 以前，你男朋友会说中文吗？ Shàng dàxué yǐqián, wǒ bù huì shuō Zhōngwén. Before I attended college, I couldn't speak Chinese.
睡觉以前，不要吃东西。 Shuìjiào yǐqián, bù yào chī dōngxi. Before going to sleep, don't eat anything.
两年以前，你认识我现在的老板吗？ Liǎngnián yǐqián, nǐ renshi wǒ xiàn zài de lǎobǎn ma? Two years ago did you know my current boss?
吃饭 以前，你洗手了吗？Chī fàn yǐqián, nǐ xǐ shǒu le ma? Before eating, did you wash your hands?
我几天以前刚刚见过她。 Wǒ jǐtiān yǐqián, gānggāng jiàn guo ta. I just saw her a few days ago.
星期五 以前，你要做完这些工作。 Xīngqī wǔ yǐqián, Nǐ yào zuò wán zhèxie gōngzuò. Before Friday, you need to finish these work.
上大学 以前，你来过上海吗？ Shàng dàxué yǐqián, nǐ lái guo shànghǎi ma? Before you went to college,did you come to Shanghai?
结婚以前，你应该先买房子。 Shēng háizi yǐqián, nǐ yīnggāi xiān jiéhūn. Before having kids, you should first get married.

Sources and further reading