C O N D I T I O N A L S 1st 2nd 3rd IF…. The zero conditional is used to talk about things which are always true – scientific facts, general truths, and so on. Zero Conditional if clause main clause Present simple, present simple. if clause main clause If you heat water to 100 degrees, it boils. main clause if clause Water boils if you heat it to 100 degrees. if clause main clause If you expose phosphorus to air, it burns. main clause if clause Phosphorus burns if you expose it to air. if clause main clause If a man looks at her, she always blushes. if clause main clause She always blushes if a man looks at her. IMPERATIVE + IF CLAUSE if clause main clause If Irene is tired, don’t disturb her. main clause if clause Don’t disturb Irene if she is tired. WILL / CAN + IF CLAUSE if clause main clause Present simple, will/can + infinitive. 1st conditional real / possible if clause main clause If the phone rings, I will answer it. if clause main clause If the weather is sunny later, we can go to the beach. 2nd conditional WOULD / COULD + IF CLAUSE if clause main clause Past simple, would/can + infinitive. unreal