D. Unless = except if (e.g. The club is for members only. You can’t go in unless you are a member (=except if you are a member))
a. Instead of unless, often possible to say if ~ not (e.g. Unless we leave now, we’ll be late. = If we don’t leave now, ~))
D1. As long as or So long as / Provided (that) or Providing (that) = if or on condition that (e.g. You can borrow my car as long as you promise not to drive too fast. Travelling by car is convenient provided (that) you have somewhere to park.)
a. When we are talking about the future, do not use ‘will’ after unless/ as long as/ so long as/ provided/ providing, but use a present tense. (e.g. I’m not going out unless it stops raining. (not unless it will stop)