Question

to solve omissions what we have must to know​

Answer 1

The simple rule is, you should know the grammar the maximum you can. Most of the editing and omission contain errors in articles, then verb forms, adjective - adverb use, degrees of adjective and many other grammatical errors.

the more you read the more you become better at finding errors. For beginners, it is advisable to start practising grammar help books from class 5th , 6th onwards, the main thing is to go slow, spend atleast 4–6 months on grammar as a whole, you will definitely improve at almost every aspect of it.