20. At a certain university, every year eight to 12 professors are granted University Merit Awards. This year among the nominated faculty are Drs. Jones, Smith, and Brown. Let A, B, and C denote the events, respectively, that these professors will be given awards.

In terms of A, B, and C, find an expression for the event that the award goes to

(a) only Dr. Jones;

(b) at least one of the three;

(c) none of the three;

(d) exactly two of them;

(e) exactly one of them;

(f) Drs. Jones or Smith but not both.