ZA5, Y4B, XC6, W3D, _____
There are three series to look for here.
The first letters are alphabetical in reverse: Z, Y, X, W, V.
The second letters are in alphabetical order, beginning with A.
The number series is as follows: 5, 4, 6, 3, 7.
QPO, NML, KJI, _____, EDC
This series consists of letters in a reverse alphabetical order.
JAK, KBL, LCM, MDN, _____
This is an alternating series in alphabetical order.
The middle letters follow the order ABCDE.
The first and third letters are alphabetical beginning with J.
The third letter is repeated as a first letter in each subsequent three-letter segment.
BCB, DED, FGF, HIH, ___
This series consists of a simple alphabetical order with the first two letters of all segments: B, C, D, E, F, G, H, I, J, K.
The third letter of each segment is a repetition of the first letter.
P5QR, P4QS, P3QT, _____, P1QV
The first two letters, PQ, are static.
The third letter is in alphabetical order, beginning with R.
The number series is in descending order beginning with 5.