But in fact,就 has several meanings.as far as I was known,it has 5 meanings at least. 1.一……就……; Can you understand it? like "once" or"if sth happens,owing to this the corresponding thing will occur. 2.高不成低不就;This maybe difficult to you,this is like something classical expression in China. 3.就理;according to several reasons. 4.Emphasis.like this sentence “我就不去”or"我就想吃“. 5.turning point,like the English word"although'.“就算你不去学校，我也要去。” Although you don't go to school,I will go. I hope these explanations above can help you.