Inserting The Missing Character Questions

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

x_za_yza_xy_aa_

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

PE_NP_ON_EO_

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

ab_bc_bb_ _abb_c

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

ef_he_g_e_gh

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

a _ c a a b _ a _ b c a a b _ a _ b _ a

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

LM_L_NL_N_M_

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

p_rrq_p_rr_p

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

r_pr_p_q_r_p