Chapter 5-10: Using Verb Tenses in Sequence
Using verbs in correct sequence is often difficult, especially for those people whose mother tongue is not English or whose mother tongue does not use a similar tense system. The situation is further complicated by the fact that context, idiom, and style play as large a role in determining tense sequence as grammatical rules.
In order to determine correct verb sequence, you must be able to identify independent and dependent clauses. The sequence of tenses in complex sentences is usually determined by the tense of the verb in the independent clause. (In compound sentences, use the tenses that fit the logic of the sentence.)