Thanks for your clear explanation, sir. By the way, I have read on a website that backshifting in reported speech and when reporting one's own thoughts is ALWAYS CORRECT though NOT REQUIRED. I have proven this to be true and very common among native speakers and writers of English, that's why sentences like "I didn't think they sold wild animals here," "I didn't know you liked that girl," "He told me his name was Bill," and "I told my friends that I was into Korean movies" are very common, even if the conditions or situations described continue to exist in the present. Now, my question is, does it always go that in the case of complex sentences if the main verb in the main clause is in the past tense, the verb or verbs in the dependent clause should also be in the past tense? If I follow this rule, I will always be correct, won't I?