Choose the correct alternative for the missing term in the series: $AZ, GT, MN, ?, YB$

Find the missing letters for the given series from the given alternatives.
$b....b...bb....,.....bbb.....bb....b$

Choose the correct alternative for the missing term:
$A, C, F, H, ?, M$

Which term comes next in the sequence: $nd, iy, dt, yo, tj, ?$

These questions are based on the following arrangement. Study it carefully and answer the questions.
$J, \star, R, 3, P, L, 2, \#, I, N, 7, O, C, @, K, 5, D, =, M, \$, 6, B, >, A, Q, 4$
What will come in place of the question mark in the following series based on the above arrangement?
$PRJ, \# L3, 7I2, @ON, ?$

Which number would replace the question mark in the series $7, 12, 19, ?, 39$.