Note :
In each of the following questions (from 21 to 30), a sequence of numbers or letters that follow a definite pattern is given. Each question has a blank space. This has to be filled by the correct answer from the four given options to complete the sequence without breaking the pattern.
BCE : EGK :: KMQ : ________
$$1000 : 512 :: .............. : 343$$
10 : 99 :: 9 : _______
AFR : ZEQ :: EMG : _____
8 : 81 :: 9 : _____
LOSE : OSVI : : GAIN : _______
HARD : DONZ : : SOFT : _________
78 : 225 :: 69 : __________
54 : 96 :: 63 : ________
34 : 1849 :: 23 :_____________