1.

SCD, TEF, UGH, ____, WKL

 A. CMN B. UJI C. VIJ D. IJT
Answer: C

Explanation:

There are two alphabetical series here.

The first series is with the first letters only: STUVW.

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

2.

B2CD, _____, BCD4, B5CD, BC6D

 A. B2C2D B. BC3D C. B2C3D D. BCD7
Answer: B

Explanation:

Because the letters are the same, concentrate on the number series, which is a simple 2, 3, 4, 5, 6 series, and follows each letter in order.

3.

FAG, GAF, HAI, IAH, ____

 A. JAK B. HAL C. HAK D. JAI
Answer: A

Explanation:

The middle letters are static, so concentrate on the first and third letters.

The series involves an alphabetical order with a reversal of the letters.

The first letters are in alphabetical order: F, G, H, I , J.

The second and fourth segments are reversals of the first and third segments.

The missing segment begins with a new letter.

4.

ELFA, GLHA, ILJA, _____, MLNA

 A. OLPA B. KLMA C. LLMA D. KLLA
Answer: D

Explanation:

The second and forth letters in the series, L and A, are static.

The first and third letters consist of an alphabetical order beginning with the letter E.

5.

CMM, EOO, GQQ, _____, KUU

 A. GRR B. GSS C. ISS D. ITT
Answer: C

Explanation:

The first letters are in alphabetical order with a letter skipped in between each segment: C, E, G, I, K.

The second and third letters are repeated; they are also in order with a skipped letter: M, O, Q, S, U.