I u want to help me

[Mr Mosaad El Hegazy]

this depends on the conjunction used in the sentence
If we use if to replace unless we don't change the tense
but if we use if to replace because or so we must change the tense as follow
future simple the conditional verb should be present simple or perfect
present simple the conitional verb should be past simple
past simple the conditional verb should be past perefect

[H0riz0n]

المشاركة الأصلية كتبت بواسطة El Hegazy

future simple the conditional verb should be present simple or perfect

present simple the conitional verb should be past simple

Thanks to Mr El Hgazy for his excellent explanation

I just want to add that in the future situations if the situation is a cause and result, we use Second Conditional

Example: I won't go with them tomorrow as I have an exam (If ....../ Unlss ....)
In this example there is no probability that I will go with them. I know in advance that I won't go with them. So in such situations, we cannot use the First Conditional
We use the Second instead
If I didn't have an exam tomorrow, I would go with them.
Unless I had an exam tomorrow, I would go with them
Dear Student, The attached file will help you differentiate among the three types

With Best Wishes
Download the attached file below