1. D’Accord 2 Leçon 5B.1
Si Clauses

2. Point de départ
Si (If) clauses describe a condition or event upon which another condition or event depends. Sentences with si clauses consist of a si clause and a main (or result) clause.
Si clauses can speculate or hypothesize about a current event or condition. They express what would happen if an event or condition were to occur. This is called a contrary-to-fact situation. In such instances, the verb in the si clause is in the imparfait while the verb in the main clause is in the conditional.
Note the use of the conditional in the following sentences:
Si j’avais de l’argent, j’achèterais une voiture.
Si nous étions en vacances, nous irions à la plage.
The conditional is used to express what would happen if a certain condition contrary to reality were met.
si – clause: IMPERFECT
result clause: CONDITIONAL
Si tu étais au lycée à Paris,
tu parlerais français en classe.
*The conditional is never used in the si-clause!!!

3. Si clauses can also express conditions or events that are possible or likely to occur. In such instances, the si clause is in the present while the main clause uses the futur or futur proche.
si – clause: present
result clause: futur / futur proche
Si j’habite à Paris,
je passerai beaucoup de temps aux musées.

4. Use a si clause alone with the imparfait to make a suggestion or to express a wish.
si – clause: imparfait
Oh non! Si je faisais mes devoirs! 

5. Summary si – clause: IMPERFECT result clause: CONDITIONAL
si – clause: present
result clause: futur / futur proche
si – clause: imparfait
Expressing a wish/making a suggestion.