21.
Which one set of letters when sequentially placed at the gaps in the given letter series shall complete it ?

ba _ cb _ b _ bab _

22.
Which one set of letters when sequentially placed at the gaps in the given letter series shall complete it ?

_ bc _ ca _ aba _ c _ ca

23.
Which one set of letters when sequentially placed at the gaps in the given letter series shall complete it ?

ab _ _ baa _ _ ab _

24.
Which one set of letters when sequentially placed at the gaps in the given letter series shall complete it ?

ab _ aa _ bbb _ aaa _ bbba

25.
Which one set of letters when sequentially placed at the gaps in the given letter series shall complete it ?

_ nmmn _ mmnn _ mnnm _

26.
Which one set of letters when sequentially placed at the gaps in the given letter series shall complete it ?

a _ n _ b _ _ ncb _ _ ncb

27.
Which one set of letters when sequentially placed at the gaps in the given letter series shall complete it ?

a _ ba _ b _ b _ a _ b

28.
Which one set of letters when sequentially placed at the gaps in the given letter series shall complete it ?

cccbb _ aa _ cc _ bbbaa _ c

29.
Which one set of letters when sequentially placed at the gaps in the given letter series shall complete it ?

bca _ b _ aabc __ a __ caa

30.
Which one set of letters when sequentially placed at the gaps in the given letter series shall complete it ?

ab __ d __ aaba __ na _ badna _ b