As long as / provided / on condition that / only if
We can use these alternatives to if if we want to emphasize the conditions surrounding the action, i.e. one thing will happen only if another thing happens.
We can also use so long as and providing (that) as alternatives to as long as and provided (that). On condition that is formally very explicit. Provided / providing are more formal than as long as / so long as. Compare the following:
We will lend you the money on condition that it is repaid within 12 months.
We will lend you the money provided (that) you can repay it within 12 months.
I don’t mind talking to the press, but only if my identity is protected.
You can have the day off today providing you agree to work a double shift tomorrow.
You can borrow my DVD player as long as you return it on Monday.
Now try some exercise to test your knowledge about conditional sentences in general:
test one, mixed exercises and tutorial