Direction: What should come in place of the questions mark (?) in the following letter series?
a, k, e, o, i, s,  ? __ ? _ , q , a , u , e 

From the given alternatives select the word which cannot be formed using the letters of the given word.

CATERING 

In the following question, select the word which cannot be formed using the letters of the given word.
 ENCOURAGING

AZBY, ? , EVFU, GTHS 

In each of the letter series, find the missing letters.

b b c – b – c a b b – a – b c a 

Direction: From the given alternatives select the word which cannot be formed using the letters of the given word.
IRREGULARITIES 

AB, DEF, HIJK, ? , STUVWX 

Direction: Study the following arrangement carefully and answer the questions given below.
C 3 # R A T 1 E J $ K @ F U 5 4 V I 6 © D 8 * H N 7 δ 2 W

How many such numbers are there in the above arrangement each of which is immediately preceded by a letter but not immediately followed by a letter?