A locker requires a three-digit code to open the lock. The code must contain one letter and two numbers, and no letter or number can be repeated. You can choose from among four letters, A, B, C, and D, and two numbers, 5 and 6.
The size of the sample space is


If a code is chosen at random, the probability that it has a letter that immediately follows an odd number is


If a code is chosen at random, the probability that D is in the code but is not in the first position is