Don't confuse the word "tense" with "time " .

Tense : indicates sense rather than time .The tense we use depends on the sense we wish to give our sentence . For example , the Present Simple can be used to indicate the future:

- He leaves to London next week .

In conditional sentences ,some of the tenses used have little connection with the time :

- If he left now ,he would arrive before nine .

So, you will avoid a lot of tense mistakes if you remember that the tense doesn't always indicate the time of the action .

I will post  in this group many discussions about the tenses of the verbs as an answer to some learners 'questions.

I hope they can read and answer the exercises here :)