We can change the order of the sentence, but if/when is always followed by the present simple. If my train arrives on time, meet you at ten Or meet you at ten I’ll o’clock. I’ll if my train arrives on time. NOT if my train will arrive on time. o’clock In first conditional sentences, if and when have different meanings. Use if when you are not sure if the situation will happen: If I pass my exams, be very I’ll happy. Use when for a situation which you know will happen: When I pass my exams, have a party. Unless has the meaning of or in this I’ll ‘if not’ ‘except situation’. go straight to the restaurant, unless you call me first. (I will go straight to I’ll the restaurant, if you call me first.) don’t Note the difference between zero and first conditional in the sentences below. If you sit in the sun, you get sunburn. (Zero conditional for a general means anyone, or people in general.) situation/ fact. ‘You’ If you sit in the sun, get sunburn. (First conditional for a specific you’ll situation. talking to you (personally) about what will happen today.) I’m 6.2 second conditional If+ past simple + would clause If I lived to be 100, I would probably be very tired, he was the President, make a lot of changes, he’d we bought the house need to sell our car we’d Use the second conditional to talk about an unreal or imaginary situation and its consequences.
We can change the order of the sentence, but if/when is always followed by the present simple. If my train arrives on time, I’ll meet you at ten o’clock. Or I’ll meet you at ten o’clock if my train arrives on time. NOT if my train will arrive on time. In first conditional sentences, if and when have different meanings. Use if when you are not sure if the situation will happen: If I pass my exams, I’ll be very happy. Use when for a situation which you know will happen: When I pass my exams, I’ll have a party. Unless has the meaning of ‘if not’ or ‘except in this situation’. I’ll go straight to the restaurant, unless you call me first. (I will go straight to the restaurant, if you don’t call me first.) Note the difference between zero and first conditional in the sentences below. If you sit in the sun, you get sunburn. (Zero conditional for a general situation/ fact. ‘You’ means anyone, or people in general.) If you sit in the sun, you’ll get sunburn. (First conditional for a specific situation. I’m talking to you (personally) about what will happen today.) 6.2 second conditional If+ past simple + would clause If I lived to be 100, he was the President, we bought the house I would probably be very tired, he’d make a lot of changes, we’d need to sell our car Use the second conditional to talk about an unreal or imaginary situation and its consequences.