Question 199069
1.Determine whether the argument is valid or invalid. 
A tree has green leaves and the tree produces oxygen.
This tree has green leaves
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 This tree produces oxygen. 
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It doesn not say that EVERY tree has green leaves and produces oxygen.
So draw two intersecting circles: one for "has green leaves", the other for "produces oxygen".
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This tree produces oxygen.
Put a point in the "has green leaves" circle".
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Does that point HAVE to be in the "produces oxygen" circle?
No
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Therefore the argument is invalid.
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Cheers,
Stan H.