@TempAccess Thank you!! That example really helped.

For question 2:

#help

I thought the argument for some before all is:

A -> B

B <-s-> C

Conclusion: A <-s-> C

So this was my answer:

Surgeons -> sight of blood

Vampires <-s-> sight of blood

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And because this statement is reversible, I changed it to:

Surgeons -> sight of blood

sight of blood <-s-> Vampire

Conclusion: Surgeons <-s-> Vampire

I don't understand how there can be no valid conclusion. Where did I go wrong?