A series is given below. In which a letter pair is not given. Choose the correct alternative from the given ones that will complete the series.
ML, RQ, WV, BA ?

Complete the following series.
C3D, E6F, G9H, I12J, ?

A series is given with one term missing. Choose the correct alternative from the given ones that will complete the series.
Constable, Head constable, ?, Inspector

DIRECTIONS: In the following question, find the missing letters in the given series.
AOP, CQR, EST, GUV, ? 

A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
AY, CW, EU, ?

In each of the letter series, find the missing letters.

a – c c a b c – a b – c – b c c 

In the following question, which one set of letters when sequentially placed at the gaps in the given letter series shall complete it?
c_e_cd_f_d_f

Which of the following letter-clusters will replace the question mark (?) in the given series?
 PK, GT, XC, OL, ?