The is a pattern of irregular yet repeated flow of expansion and contraction of aggregate economic activity.

This is called a business cycle!

A business cycle is defined as an "up and down movement"- this corresponds to expansion and contraction. This expansion and contraction is measured for example in the Gross Domestic Product (GDP) of a country.

Business cycles last from 2 to 12 years.

Sometimes but itt depends, their is a lot if drugs on campus too so you really can't just say that