For example, choose male doctor a, female doctor b, and then choose male doctor C.

And choose male doctor C, female doctor B, and then choose male doctor.

These two situations are the same.

Therefore, this topic should be selected by classification and grouping.

Divided into two categories, choose two male doctors, 1 female doctor c (5,2) * c (4, 1)=40.

Choose 1 male doctor and 2 female doctors. C(5， 1)*C(4，2)=30。

* * * There are 70 kinds.