Explanation :

The given series follows the pattern +2, +3, +4, +5 and so on.

So, the missing term is J.

Explanation :

The given series is continuous and contains only consonants terms.

So, the missing term is K.

Explanation :

ACE - one letter is skipped within this group and start from letter A. The first letter of the first group is to move one step forward to obtain the first letter of the second group.

BDF - one letter is skipped within this group and start from letter B. The first letter of the second group is to move one step forward to obtain the first letter of the third group.

CEG - one letter is skipped within this group and start from letter C. The first letter of the third group is to move one step forward to obtain the first letter of the fourth group.

The next group should start with D and skip a letter.

DFH - one letter is skipped within this group and start from letter D. The first letter of the fourth group to is move one step forward to obtain the first letter of the fifth group.

EGI - one letter is skipped within this group and start from letter E. The first letter of the fifth group is to move one step forward to obtain the first letter of the sixth group.

So, the missing term is DFH.

Explanation :

The given series involves three steps :

1^st Step : 1^st letter of each group in the series follows the pattern ⇒ J, K, L, M, N

2^nd Step : 2^nd letter of each group in the series  follows the pattern ⇒ A, B, C, D, E

3^rd Step : 3^rd letter of each group in the series follows the pattern ⇒ K, L, M, N, 0

So, the missing term is NEO.

Explanation :

The given sequence is a combination of two alphabetical series.

The first series is with the first letters only : S, T, U, V, W

The second series involves the remaining letters : CD, EF, GH, IJ, KL

So, the missing term is VIJ.