How to Tackle a Sentence Correction Problem

1. Check for Subject-Verb Agreement (when subject is hidden)
1a. Skip the middleman and the warm-up:

• Prepositions
• Modifiers (past participles, present participles, relative pronouns, prepositions, appositive)
  
• Subordinate clauses (dependent clause with subject and verb and begins as a subordinate conjunctions)
  

1b. Does it exist?
1c. Does it agree in number?

• Either or/Neither Or (verb follows the nearest noun)
• Either/Neither (verb is always single)
• And vs. Additive Phrases
• Collective Nouns
• Indefinite Pronouns
• Each and Every
  
• Quantity words and phrases
  

1d. Does it make sense?

Watch out for the following words in red and what it leads to:

Subject-Verb
And - Agree in number
Additive - As well as -Agree in number

Neither (without OR) = Singular
Neither/Either Or = Follows the noun closing to it

Pronouns/Nouns

Everytime the following appears, be on the look out!
Deadly Five: They, Their, Them, It, Its -> Pronouns/Nouns
Demonstrative Pronouns: This, That, These, Those -> Pronouns/Nouns

Verb Mood
If -> Verb Mood > Hypothetical Subjunctive
Bossy Verbs -> Verb Mood -> Command Subjunctive

Comparisons
Comparison signals: Like, unlike, as, than

Comparative ad Superlative: Between, Among

Verb Tense

Since - the word "since" show that the action is continuing from the past to the future. Therefore you use present (current) perfect (past).

Current = Has

Perfect= Been

Present Perfect: Has been

Example: Since 1987, the record HAS BEEN (Present Perfect) BROKEN (Past Tense) 8 Times.