For Q1: Would it also be accurate to negate the statement by saying "Some non-water breathing mammals have limbs"? Would that logically be the same as "Some non-water breathing mammals don't have limbs"? Do you have to negate the necessary condition?

I am having the same issue. I paid for the $69/month subscription. Is there another subscription that I need to purchase through LSAC?

#feedback it would be great to get some "test like" examples incorporated to each lesson to better understand the importance of certain concepts.