
Only if
Conditional Permission
Indicates permission is granted only when a specific requirement is fulfilled.
You may have dessert only if you eat your vegetables.
Implicit Limits
Highlights a single situation where an action or event is allowed, excluding other possibilities.
I'll lend you the book only if you return it next week.
Emphasis on Condition
Accentuates the importance of the condition that must be met for the result to occur.
He'll agree to the deal only if the terms are favorable.