- For Teachers
All above expressions mean 'if' or 'on condition that'
Ex:You can use my car as long as/so long as you drive carefully
She'll pass the exam provided (that)/providing(that) she studies hard.
*Unless = 'except if'
Ex: We'll be late unless we hurry = We'll be late if we don't hurry.
When you are talking about the future, do not use will after unless/as long as/ provided/ providing. Use a present tense: I'll see you tomorrow unless I have to work late.
I extract it from 'English grammar in use-2nd edition' of Raymond Murphy because I find it helpful in writting, we can replace 'if' with some other words.