以前
yǐ qián
Before a specific time with "yiqian"
以前 works exactly like 以后, but for what comes before.
Time / Verb + 以前
How it works
Put the time or the action first and 以前 after it: 十点以前 (before ten), 睡觉以前 (before sleeping). The mirror image of 以后, with the same word order.
Standing alone at the front of a sentence, 以前 means "in the past" — 以前我不会说中文. That use is drilled at HSK 3.
Examples
shí diǎn yǐ qián, wǒ zài jiā
十点以前，我在家。
Before ten, I'm at home.
shuì jiào yǐ qián wǒ xǐ huan kàn shū
睡觉以前我喜欢看书。
I like to read before sleeping.
lái zhōng guó yǐ qián, tā bú huì yòng kuài zi
来中国以前，他不会用筷子。
Before coming to China, he couldn't use chopsticks.