Unless, as long as, provided, providing

Unless (Except if, Only if)

• You can't touch that unless you buy it
• You can't open it unless you have the key
• I'll see you tomorrow unless I have to work late
• Can I buy those shoes? - Not unless you need them
• We can take a taxi to the restaurant - (unless you'd prefer to walk) or (unless you'd rather walk)
• You can't go into the party unless you are invited
• Can I tell her my opinion? Not unless she asks you
• Unless you have a car, it's difficult to get there
• Unless you speak slowly, she won't be able to understand you
• Unless you study more, you won't pass the exam
• Unless we leave now, we'll be late
• I'm not going out unless it stop raining

As long as / So long as / Providing (that) / Provided (that) (If, On condition that)

• You can touch that as long as you buy it
• You can borrow my camera as long as you promise to look after it
• You can drive so long as you promise to drive carefully
• Having a car is convenient providing (that) you can afford it
• Travelling by plane is convenient provided you don't have afraid of flying
• You can lift weigh providing your doctor approves it
• Providing the weather is good, we're going to have a picnic
• Providing I have enough money for tickets, we'll go to the concert