| Time reference | Verb in main clause | Verb in conditional clause | ||
|
future |
will, (might) |
Present, usually present simple |
 | If you talk to Jenny, she'll help you. (Si hablas con Jenny, te ayudará.) |
| We'll have a barbecue if it doesn't rain. (Haremos una barbacoa si no llueve.) |
| We might have a barbecue if it doesn't rain. (Tal vez hagamos una barbacoa si no llueve.) |
We can also make conditional sentences with unless (a menos que), as long as (siempre que) and provided (or providing) (that)(siempre que), e.g.:
| I can't help them unless they give me more information. (No las puedo ayudar a menos que me den más información.) |
| Unless she finds the receipt, there is nothing we can do. (Si no encuentra el recibo, no hay nada que podamos hacer.) |
| You can stay and watch as long as you keep quiet. (Os podéis quedar y mirar siempre que os mantengáis en silencio.) |
| They will sign the contract provided/providing the new clause is inserted. (Firmarán el contrato siempre que la nueva cláusula esté incluida.) |
| Provided/providing that we finish by tomorrow, they will pay us at the end of this month. (Siempre que acabemos mañana, cobraremos al final de este mes.) |
Notice that in case is similar, but it does not express a condition, e.g.:
| I'll take my umbrella in case it rains. (Me llevaré el paraguas por si llueve.) |
| They packed extra jerseys in case the weather turned cold. (Empaquetaron más jerseis por si empezaba a hacer frío.) |