What helped me with these problems is remembering the negation diagram for each quantifier. Immediately when I see "all" I know that the negation is: some A are not B.

So for #1 All non-water breathing mammals have limbs.

Becomes: Some mammals do not have Limbs.

Hope that helps! You got it!

I am currently in a long term healthy relationship, and regardless I have made it clear that studying is my priority. We are all opening a new chapter of our lives and are young. It’s important we prioritize ourselves over any relationship, because we have the rest of our lives to sacrifice things for a partner. This is not the time.