“Chinese is not hard, really. ” after the lesson, a child commented. Yes, indeed, Chinese, especially Spoken Mandarin, is not very difficult. Look, based on the numbers, we can conjugate weekdays(星期 xīng qī ), month（月 yuè ) and year(年 nián ).
Now when we talk about yesterday, today and tomorrow, they all share one word – 天（tiān ), which means 1. day, 2. sky. What you need to remember is only three different words indicating the time span:
昨天（zuó tiān ） — yesterday
今天 (jīn tiān ) — today
明天 (míng tiān ) — tomorrow