"Si" clauses, also known as conditional clauses or "si" sentences, are a grammatical structure used to express hypothetical or conditional situations.
These sentences consist of two parts: the "si" clause and the main clause.
The "si" clause introduces a condition, and the main clause provides the consequence or result if that condition is met.
There are three main types of "Si" sentences in French:
when the "si" clause uses the present
when the "si" clause uses the imperfect tense
when the "si" clause uses the pluperfect
1. Si + Présent
Si + présent, futur simple
When the present tense is used in the "si" clause, the main clause (the consequence) can be in the future.
Example: Si tu économises de l'argent, tu pourras acheter une voiture.
(If you save up, you will be able to buy a car.)
Si + présent, présent
When the present tense is used in the "si" clause, the main clause can be in the present.
Example: Si on travaille, on peut réussir.
(If we work, we can succeed.)
Si + présent, impératif présent
When the present tense is used in the "si" clause, the main clause can be in the imperative present.
Example: Si tu as le temps, fais-le!
(If you have the time, do it!)
Be careful! The "si" clause can NEVER be in the future tense, only the main clause can be.
Note that you can sometimes come across sentences which are structured with the main clause first.
Example: Tu pourras acheter une voiture si tu économises.
2. Si + imparfait
Si + imparfait, conditionnel présent
When the imperfect is used in the "si" clause, the main clause is in the conditional present.
Example: Si nous étions riches, nous achèterions une maison.
(If we were rich, we would buy a house.)
Be careful! The "si" clause can NEVER be in the conditional, only the main clause can be.
Note that you can sometimes come across sentences which are structured with the main clause first.
Example: Nous achèterions une maison si nous étions riches.
3. Si + Plus-que-parfait
Si + plus-que-parfait, conditionnel passé
When the pluperfect is used in the "si" clause, the main clause is in the conditional perfect.
Example: Si nous étions venus, il aurait été content.
(If we had come, he would have been happy.)
Note that you can sometimes come across sentences which are structured with the main clause first.
Example: Il aurait été content si nous étions venus.
Be careful!
Don't confuse "si" clauses with another use of the word 'si'.
The word 'si' can also be used to introduce indirect questions.
Example: Je ne savais pas si tu voulais que je le fasse.
(I didn't know if/whether you wanted me to do it.)