If is the default word for setting up a condition, but it is not the only one. English has a whole vocabulary of conditional connectors, each with its own shade of meaning — negation, requirement, preparation, hypothesis, limitation.
This lesson groups them by function. The verb patterns after each connector are the same as in plain conditionals (present for the first type, past for the second, past perfect for the third).
Negation: unless
Unless means if… not. It replaces a negative condition with a positive one and keeps the sentence shorter.
Use unless mainly in first-conditional situations. It works in the second conditional too, but feels heavier there and is usually replaced with if… not. It is not used for impossible past conditions — the third conditional prefers if… not had.
Warning: never combine unless with a second negative. The word already carries the negation.
Requirement: as long as, provided that, on condition that
These phrases introduce a condition that must be met. They feel stronger than a plain if — the speaker is setting a limit or a requirement.
As long as and so long as are neutral and common in speech. The condition is presented as a boundary for the main action.
Provided (that) and providing (that) are more formal and common in writing. The word that is optional and often dropped. Provided is preferred over providing in careful prose.
On condition (that) is the most formal of the set. It signals a binding or official requirement and is common in contracts, legal writing, and news reports.
Preparation: in case
This is the connector most often confused with if. In case does not describe a condition — it describes a precaution taken because of a possible future event.
Compare carefully:
With in case, the action happens first, as preparation. With if, the action depends on the condition actually occurring. This distinction is one of the sharpest tests of B1–B2 accuracy.
In case is followed by the present simple for future meaning (never will), and by the past simple for past preparation: She left early in case the traffic was heavy.
Hypothetical: suppose, supposing, imagine, what if
These invite the listener to picture a situation. They are less formal than if and often appear at the start of a question or a soft proposal.
The verb tense follows the same logic as a normal conditional: present for realistic hypotheses, past for unlikely ones, past perfect for past ones. Supposing and suppose are interchangeable; imagine and what if are slightly more conversational.
Limitation: even if, only if, whether… or not
These sharpen the boundaries of the condition — either by ignoring it, narrowing it, or neutralising it.
Even if means the condition makes no difference to the result. The outcome stays the same either way.
Only if stresses that this is the sole condition under which something will happen. It is more restrictive than plain if.
When only if starts a sentence, the main clause uses inversion: Only if you confirm within 48 hours is the offer valid. This formal pattern is optional; keeping only if in the middle is also correct.
Whether… or not tells the listener that the result will be the same under both outcomes. The condition is mentioned only to be dismissed.
Common mistakes
Confusing in case with if
Double negatives with unless
Wrong tense after conditional connectors
Mixing unless with if
Using unless for impossible past conditions
Confusing even if with only if