4. Put each of the following categorical syllogisms into standard form, (major premise, minor premise, conclusion) supplying the missing proposition if it is an enthymeme. Be sure that both the subject and predicate are clearly phrased as classes of things. Also determine the validity of the syllogism remembering to use the syllogism rules (or other methods.)

a) Some shoes are comfortable but some shoes are not stylish. Therefore, some comfortable shoes are not stylish.

b) No plant can live without water because all living things need water and all plants are living things.

c) Grapes are toxic to dogs but not to humans. Therefore, some things that are toxic to dogs are not toxic to humans. (explain why traditional logic should be used to determine validity here)