Subjunctive

Question 1

When to use the subjunctive?

Answer 1

The subjunctive mood is used to express actions or ideas which are subjective or otherwise uncertain: will/wanting, emotion, doubt, possibility, necessity, judgment…

It is nearly always found in dependent clauses introduced by que or qui, and the subjects of the dependent and main clauses are usually different.

   Je veux que tu le fasses.I want you to do it. 
   Il faut que nous partions.it is necessary that we leave.

Question 2

How to form the subjunctive?

Answer 2

To conjugate all regular verbs ending -ER, -IR, and -RE, as well as some irregular* ones, take the 3rd person plural ils form of the present tense of the verb, drop the -ent ending to find the stem, and add the subjunctive endings.

Ils parlent changes to parl-

Je parle
Tu parles
Il parle
Nous parlions
Vous parliez
Ils parlent

Don’t forget that several verbs have an irregular third person plural: ils boivent, ils prennent, ils viennent, ils envoient

Je boive
Tu boives
Il boive
Ils boivent

For these irregular sub. verbs, the nous and vous form use the stem of the nous present: nous buvions, vous buviez, nous envoyions, vous envoyiez

And finally, two verbs have irregular stems as well irregular endings:
 	avoir	  	    	    	    	    	    	    	    	    
   ... que je (j')	aie	
   ... que tu	aies	
   ... qu'il/elle/on	ait
   ... que nous	ayons	
   ... que vous	ayez	
   ... qu'ils/elles	aient

Etre: sois
sois
soit
soyons
soyez
soient

Question 3

do you put the verbs following croire, espérer, and penser in the subjunctive?

Answer 3

Only when it is a negative statement or expresses doubt. Ils ne croient pas qu’elle parte.

Question 4

what conjunctions always trigger the subjunctive unless that subject of the main clause is the same as the subordinate clause?

Answer 4

à condition que
à moins que (unless)
afin que (in order that)
avant que (before)
bien que (although)
de peur que (for fear that)
en attendant que (waiting for)
jusqu'à ce que (until)
pour que (so that)
pourvu que (provided that)
quoique (although)
sans que (without)

Question 5

when do you use the past subjunctive?

Answer 5

The past subjunctive is used for the same reasons as the present subjunctive - to express emotion, doubts, etc. The past subjunctive is used when the verb in the subordinate clause - the verb that follows que - happened before the verb in the main clause.

The past subjunctive may be used in a subordinate clause when the main clause is in the present tense:

Je suis heureuse que tu sois venu hier.
I’m happy that you came yesterday.

Nous avons peur qu’il n’ait pas mangé.
We’re afraid that he didn’t eat.

Or it may be used in a subordinate clause when the main clause is in the past tense. Note that if the main clause did not call for the subjunctive, the subordinate clause would have been in the past perfect, because the subordinate clause happened before the verb in the main clause. Therefore, the subordinate clause should technically be in the pluperfect subjunctive. But that is replaced by the past subjunctive in all but the most formal French.

Il doutait que vous l’ayez vu.
He doubted that you had seen it.

J’avais peur qu’ils soient tombés.
I was afraid that they had fallen.

Question 6

How do you form the past subjunctive?

Answer 6

Like all French compound conjugations, the past subjunctive may be subject to grammatical agreement:

When the auxiliary verb is être, the past participle must agree with the subject 
When the auxiliary verb is avoir, the past participle may have to agree with its direct object 

AIMER (auxiliary verb is avoir)
j'	aie aimé	 	nous	ayons aimé
tu	aies aimé		vous	ayez aimé
il,
elle 	ait aimé		ils,
elles 	aient aimé

DEVENIR (être verb)
je sois devenu(e) nous soyons devenu(e)s
tu sois devenu(e) vous soyez devenu(e)(s)
il soit devenu ils soient devenus
elle soit devenue elles soient devenues

SE LAVER (pronominal verb)
je me sois lavé(e) nous nous soyons lavé(e)s
tu te sois lavé(e) vous vous soyez lavé(e)(s)
il se soit lavé ils se soient lavés
elle se soit lavée elles se soient lavées