This document discusses the uses of the words "as", "just as", and "since". It provides examples of how each word is used: - "As" is used to indicate two things happening at the same time or together over a period of time. It can also replace "because" in informal contexts. - "Just as" emphasizes that two things happened exactly at the same moment. - "Since" is better used when referring to a period of time, such as "since she moved" or "since we have time". The document compares the uses of "as" and "when", and provides guidance on the proper contexts to use each word.