Can anyone give me advice regarding improving pairing strength in verbal section ?
I would first start off by improving your knowledge of the vocab. On the vocab mountain, pay attention to how the word is used in the example sentence, as well as the sample synonyms.
Also, I would go to the Pairing exercise under the Skill Building tab on the GregMat site and try some questions. If you do not know the meaning of the words, then go back and continue to build your vocab. If you know the words individually but did not consider them synonyms, then I would look into why you thought they were different and would take note that they are synonyms and try to apply that knowledge going forward.