What should come next in the following letter sequence?

A A B A B C A B C D A B C D E A B C D

A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
A, C, F, H, K, ?

A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
LOQ, SVX, ZCE, ?

A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
A, E, I, M, ?

A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
ACE, FHJ, KMO, ?

In the following question, select the related letter/letters from the given alternatives.

CPR : ERT : : DQS : ?

In the following question, select the odd letter/letters from the given alternatives.

A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.

PRQ, NPO, LNM, ?, HJI

A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
FK27, LQ64, RW125, ?