(8) The provincial traditional Chinese medicine hospital plans to arrange 6 doctors for duty from May 1st to May 3rd, requiring each person to be on duty for 1 day, with 2 people scheduled each day. If doctor A cannot be on duty on the 2nd, and doctor B cannot be on duty on the 3rd, then the number of different ways to arrange the duty schedule is $\qquad$ kinds.
Solution: Divide into two categories
(1) If A and B are on duty on the same day, then they can only be scheduled on the 1st, with $C_{4}^{2}=6$ ways to arrange;
(2) If A and B are not on duty on the same day, there are $C_{4}^{1} C_{3}^{1} \times 3=36$ ways to arrange, so there are a total of 42 methods.