涛涛25--11

Q11

Of the three-digit positive integers that have no digits equal

to zero, how many have two digits that are equal to each

other and the remaining digit different from the other two?

A.      24

B.      36

C.      72

D.     144

E.      216

请教思路~~!!  1/2C(9,2)C(8,1)=144 对吗?

9^3-P（3，9）-9=216