Who / Whom / Whose / Who's

In each example, indicate the correct form of who:

1. The professor is the one ___ lectures to the class.

whom who

2. ___ books are these?

Who's Whose

3. To ___ it may concern:

whom who

4. ___ the author of the novel that begins with the line "[i]t was the best of times, it was the worst of times"?

Whose Who's

5. ___ keeps shutting off the computer when I leave my desk?

Whom Who