zhī qián
吃饭之前要洗手
chī fàn zhī qián yào xǐ shǒu
You should wash your hands before eating
一个月之前我还遇到过他
yí gè yuè zhī qián wǒ hái yù dào guò tā
I met him a month ago
他们站在队旗之前举手宣誓。注意多指时间，少指处所。
tā men zhàn zài duì qí zhī qián jǔ shǒu xuān shì. zhù yì duō zhǐ shí jiān, shǎo zhǐ chù suǒ.
They stood before the team flag and raised their hands to take an oath. Note that it mostly refers to time, rarely to location.