I always seem to get stuck on when to use HAS or AS. Is there a simple way in which to remember which word is the correct one?

Grateful thanks,

Has is a form of the verb to have so means "belonging to".
As means "like".

Eg. John has a blue car as does Pete. 
Can you give an example of a case about which you are confused?
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 ALT's reply was promoted to an answer.
Thanks for your clear and precise clarification on this matter. I too have always struggled with Has and As. You are the first person to explain the definition and the context upon which they can be applied.