How important is English Grammar in CAT?

Just like the basic operations of addition, subtraction, multiplication and division for the core concepts of any quantitative problem, the Grammar of the language can be called as its building block, which provides the language with a sense of clarity and logic.
Even though CAT paper hasn’t been asking questions directly from English Grammar for some time now, the importance of it can’t be side-lined at any stage, given that the concept will always stay in any type of verbal, reasoning or even quantitative sections to understand the questions clearly and reach the correct answers as soon as possible.
You don’t have to go back to your school Grammar book always page by page to clear your concepts. Most of the questions that in CAT that want you to apply the concept of English Grammar directly or indirectly will probably won’t require you to be an expert of the field, but a handy knowledge of concepts of subject and verb, articles, tenses, pronouns and adjectives.