So you see, we are going over the principles, the concepts little by little. We have seen what a proposition was, we have seen what a subordinate proposition was, now let us see what this concept of concordance of tenses means.
The concordance of tenses is the correspondence, it is the agreement of tenses between the main clause and the subordinate clause. When we change the tense of the verb of the main clause, we must also change the tense of the verb of the subordinate clause. We will take examples to make it clearer.
Let's take the sentence "I watch TV while he sleeps." So we have a main clause, "I watch TV," and we have a subordinate clause, "while he sleeps." "He sleeps," the verb of the subordinate clause is in the present tense.
If I change the tense of the verb in the main clause and instead of saying "I watch TV" I say "I was watching TV", well I have to change the verb in the subordinate clause as well. I can't say "I was watching TV while he was sleeping". That doesn't work. Since I changed the tense of the main clause, the tense of the verb in the main clause, I have to change the tense of the subordinate clause as well. So "while he was sleeping" becomes "while he was sleeping". I have two verbs in the imperfect tense. I was watching TV while he was sleeping. That's tense agreement.
Let's move on to a slightly more technical part. Again, don't panic, take your time. We have all the time in the world to understand these concepts. This is what concerns the order of actions. This will be important to understand when talking about the concordance of tenses in the past. What we need to understand is that the verb oman whatsapp number data of the subordinate clause can express an action that is prior to the action of the main clause. Prior means "which takes place before". Or it can be an action that is simultaneous, that is to say, which occurs at the same time as the action of the main clause. Or, the action of the subordinate clause can be subsequent to the action of the main clause, which means that it occurs after.
For example, if I say "I watch TV while he sleeps", here, the two actions, the action of the main clause and the action of the subordinate clause, they are simultaneous, they occur at the same time. But this is not always the case. In an example that we saw previously, the action of the subordinate clause takes place before the action of the main clause, it is the sentence "I read the book that he gave me". He necessarily gave me the book before I read it. So the action of the subordinate clause takes place before the action of the main clause.
And the fact that the action of the subordinate clause occurs at the same time, before or after the action of the main clause, will have an impact on the concordance of tenses. When the main verb is in the present tense, the subordinate verb will be conjugated in the present tense to express simultaneity, that is, actions that take place at the same time.
The verb of the main clause is in the present tense, the verb of the subordinate clause is also in the present tense, since there is simultaneity.
If we want to express anteriority, that is to say if we want to show that the subordinate action took place before the main action, well we will conjugate the verb of the subordinate in the imperfect or the past tense.
For example: Tom says he did his homework. The verb of the main clause is in the present tense, the action of saying "Tom says" is in the present tense; the fact of doing his homework was done in the past, so we have the anteriority of the subordinate clause, so we conjugate it here in the past tense. At the time Tom speaks, he had already done his homework.