Zero and first conditionals
It will be better if we met / meet at 4 pm.
It will be better if we meet at 4 pm.
If you need / do need more information about how to do the experiment, ask the teacher.
If you need more information about how to do the experiment, ask the teacher.
He’ll be happy if you could / can help him work out the solution to this maths equation.
He’ll be happy if you can help him work out the solution to this maths equation.