The Sentence Correction questions test your knowledge of correct grammatical usage and your sense of clear and economical writing.

Choose answers according to the norms of standard written English for grammar, word choice, and sentence construction.

Your selected answer should express the intended meaning of the original sentence as clearly and precisely as possible

Sentence Correction question looks like this-

1. When Charlene goes to the park, she likes to run, swim, and to play basketball.

A. she likes to run, swim, and to play basketball
B. she likes to run, swim, and play basketball
C. she likes running, to swim, and to play basketball
D. she likes running, swimming, and to play basketball
E. she likes all of the following, to run, swim, and to play basketball

You're given: a sentence with one section underlined, and five answer choices. The underlined portion is reproduced five different ways in the answer choices - choice A will always be identical to the underlined portion of the sentence. Your task is to find the answer choice which is most grammatically correct according to the rules of Standard Written English. Sometimes more than one answer choice will appear to be free of grammatical errors. This is not a mistake. Style conventions must be taken into consideration as well: when this occurs, you must look for the answer that is most concise, and/or is free of redundancy.

The basic approach to Sentence Correction questions is as follows:

Read the complete sentence.

Do not simply read the underlined part of the sentence, because context may be important in determining the correct answer. As mentioned above, choice A will always be a copy of the original underlined part of the sentence. If you cannot find any errors, grammatical or otherwise, in the original sentence, choose A, and move on. Don't worry about spelling, capitalization, or punctuation; they are not covered in Sentence Correction questions. If you do find an error in the underlined portion, or if you're not sure, proceed to step two.

Dissect-

The GMAT tests only a limited number of grammar error types. After you've read the sentence, look for clues indicating what grammar rule the question is testing. These grammar rules, and the clues to look for, will be covered in more detail in the next section. Keep an eye out for:
Agreement Issues: Look for pronouns, verbs, and nouns: do they agree?
Modifiers: Look for introductory phrases set off by a comma: is the modifier used correctly?
Parallels: Look for commas separating words in a list, as well as expressions such as not only...but also, both..and, either...or, neither...nor: is everything parallel?

Compare-

After you've dissected the question, compare answer choices and note how they differ. Look for the answer choice that preserves the meaning of the original sentence without creating new errors. Eliminate answer choices with grammar errors. Use the process of elimination scrap paper charts to narrow your choices.

The GMAT tests only a limited number of grammar error types.

Therefore, you only need to learn a limited number of grammar rules – you don't need to master every grammatical and stylistic rule of Standard Written English to do well on the GMAT.

A. Subject-Verb Agreement
B. Modifiers
C. Parallelism
D. Pronoun Agreement
E. Verb Time Sequences
F. Comparisons
G. Idioms