this is why I have trust issues

why does negations not work here?

in the video he says we cannot reach the conclusion because it's the opposite. But why can't the negated conclusion be possible?

#help (Added by Admin)

should we do the conditional diagrams for each question in the actual exam?

I'm wondering how I can do the questions without the diagrams, but at the same time, coming up with the diagrams will take a lot of time.

#help (Added by Admin)