Philosophy Critical Thinking question

A.  Can a proposition support another proposition if it (the first proposition) is false? Explain why/why not.

B. Determine whether the following arguments are formally valid. If they are not, present an argument that follows the same pattern, but has (i) all true premises and (ii) a false conclusion.

1.  Stevie is a cat.  
    So, Stevie is a mammal

2.  If all cats are female, then some dogs are male.
    Not all cats are female.  
    So, not all dogs are male

3.  If the moon is made of cheese, then there are mice on the moon.
   There are no mice on the moon.  
   So, the moon is not made of cheese.

4. The Earth is a planet.  
   So, the Earth is a planet.