Find the missing pattern.
C22D, ____, C64D, C85D, C106D

In each term, the letters 'C' and 'D' remain fixed at the beginning and the end. Let's observe the numbers in the sequence:
22, ____, 64, 85, 106

Let's find the difference between consecutive known numbers:

* $106-85=21$
* $85-64=21$

Since the difference is constant ($21$), the numbers form an Arithmetic Progression (AP) with a common difference of $21$.

Thus, the missing number is:

$$22+21=43$$

Verifying with the next term: $43+21=64$ (which matches).

Therefore, the missing pattern is C43D.