Luyện ngữ pháp English Grammar in Use (Unit 115: Unless As Long as Provided/ providing)
Unless
Study this example situation:
You can,t go in unless you are a member.
This means:You can't go in except if you are a member.You can go in only if you are a member.
Unless = except if.
As long as / provided / providing
Unless / as long as etc. for the future