For the purposes of studying and PTs, how significant is the priority of the question?

It took me a while, but I finally got the Kumar example. It's about the form of the argument, not the content.

late-->5+ A-->B

late A

_

5+ B

The Kumar example swaps the A and B. It's not the right form, so it's not valid. It doesn't matter what A and B are, you can't swap them.

If what matters is the form and not the content, why would the tense shift in 2.2

The sentence is "A teacher earns respect if she fosters a love of learning."

The solution gives the following sentence for the contrapositive: "If a teacher does not earn respect, then she did not foster a love of learning."

I wrote "does" instead of "did". If the focus is on form, there isn't a reason to change the verb tense from does to did. What am I missing and does it matter?

I'm almost surprised that pirates and global warming weren't used.

Since the decline of pirates, global warming has been on the rise. Thus, global warming and the pirate population are negatively correlated.

It actually helped me to draw out the diagram for this one. A circle for A, Circle B intersecting A, and Circle C intersecting B. A and C don't have to intersect, so the conclusion from the Lawgic that A←s→C isn't valid. Works in my brain.