ab _ _ baa _ _ ab _

The series is abc/bca/cab/abc/bca, Thus, the letters change places in a cyclic order.

The series is babc/babc/babc. Thus, the pattern 'babc' is repeated.

The series is cabbac/cabbac/cabbac. Thus, the pattern 'cabbac' is repeated.

The series is baab/baab/baab/baab. Thus, the pattern 'baab' is repeated.

The series is acac/abab/acac/abab/acac. Thus, the pattern acac/abab is repeated

The series is abb/aaabbb/aaaabbbb/a. Thus the letters are repeated twice, then thrice, then four times and so on.

The series is nnmm/nnmn/nnmm/nnmm. Thus, the pattern 'nnmm' is repeated.

The series is abncb/abncb/abncb. Thus, the pattern 'abncb' is repeated.

The series is abb/abb/abb/abb. Thus, the pattern 'abb' is repeated.

The series is ccc bbb aaa/ccc bbb aaa/c. Thus, the pattern ccc bbb aaa is repeated.