1. In back of means located behind.
Pattern 1: noun + in back of + noun
There is a beautiful tree in back of our house.
Pattern 2: verb + in back of + noun
Your sister sits in back of me in class.
Forever Young Naturally Eating
Drinking Water Drink enough water
Drink a glass of water after getting up and make another glass the last liquid you sip before bed. When you work, drink often from a glass of water close to your desk and take regular water-cooler breaks to fill up. Keep a bottle of water by your side at the gym.