Using universal modus tollens, fill in the following:

Answers:

1. People who are good at logic make good programmers.
   Buffy would not be a good programmer.
     Buffy is not good at logic.
   
   
   
2. My professors are happy when I pay close attention to their lectures.
   I fell asleep during my classes today.  (Something close to this answer will do!)
     My professors are not happy today.
   
   
3. x, k  Z, if x = 2k for some integer k, then x is even.
   x is not even.
    x2k for any k.
   
   
   
4. Animals at the bottom of the food chain are very nervous.
   Lions are not nervous.
     Lions are not at the bottom of the food chain.