p.22 Problem B:

3. necessarily true because the property of being "good building material" is the same as being "useful for building things"

4. necessarily false because a three story building cannot be only two stories tall

5. contingent because its truth depends on the definition of "mammal", which could change

p.22 Problem C:

2. not necessarily equivalent -- the first sentence is a universal statement about all mammals while the second is a conditional about one particular mammal

3. not necessarily equivalent -- they have nothing to do with each other (in as much as logic is concerned)

4. necessarily equivalent -- being "44th" means by definition you are immediately after "43rd"

p.22 Problem F:

1. impossible because if M2 holds, then M1 says Socrates is mortal, but M3 says Socrates is not mortal

3. jointly possible (if immortal people existed)

4. jointly possible

p.22 Problem G:

2. possible -- if the premises are false, then it is impossible to devise a counterexample, meaning the argument would be considered valid

5. impossible -- being contingent means it could be either true or false but being a necessary truth means it must always be true

8. possible -- being necessarily equivalent just means their truth values match and being jointly impossible means it is not possible for them to both be simultaneously true

10. possible -- jointly impossible just means that all cannot be true