1. Represent August 12, 2018 using eight digits as $12-08-2018$, where each digit appears exactly twice. Then including August 12, the number of days in 2018 that satisfy this property is ( ).
(A) 5
(B) 6
(C) 7
(D) 8
(E) 9
1. B.
Since each digit appears twice, and the digits of 2018 are all different, the month and day must be composed of 2018. Therefore, the possible months are: 01, 02, 08, 10, and 12.
01 month can have 28 days; 02 month can have 18 days; 08 month can have 12, 21 days; 10 month can have 28 days. In total, there are 6 possibilities.