Imperative Mood

For -ER verbs:

The imperative conjugations for nous and vous are the same as the present indicative, minus the final s for the tu form.

Verbs which are conjugated like -ER verbs (the indicative tu ends in -es), such as ouvrir and souffrir, follow the same rules as -ER verbs and drop the final s for tu. 

The imperative conjugations for all regular and most irregular -IR and -RE verbs are the same as the present indicative conjugations (meaning keep the s for tu).

Four irregular imperative verbs:
avoir
   (tu) aie
   (nous) ayons
   (vous) ayez

être
   (tu) sois
   (nous) soyons
   (vous) soyez

savoir
   (tu) sache
   (nous) sachons
   (vous) sachez

vouloir
   (tu) veuille
   (nous) n/a
   (vous) veuillez

http://french.about.com/od/grammar/a/imperative_2.htm

Future Tense

For future tense, all we need to do is use the infinitive form as root for -ER or -IR verbs and for -RE verbs, remove the final -e and add the future tense endings:

je          -ai
tu          -as
il           -a
nous     -ons
vous     -ez
ils         -ont

Infinitive	Future Root	Meaning	Similar Behaving Words
acheter	achèter-	to buy	achever, amener, emmener, lever, promener
acquérir	acquerr-	to acquire	conquérir, s'enquérir
appeler	appeller-	to call	épeler, rappeler, renouveler
aller	ir-	to go
avoir	aur-	to have
courir	courr-	to run	concourir, discourir, parcourir, more
devoir	devr-	must
envoyer	enverr-	to send
essayer	essaier-	to try	balayer, effrayer, payer
essuyer	essuier-	to wipe	appuyer, ennuyer
être	ser-	to be
faire	fer-	to do, to make
falloir	faudr-	have to
jeter	jetter-	to throw	feuilleter, hoqueter, projeter, rejeter
nettoyer	nettoier-	to clean	employer, noyer, tutoyer, more
pleuvoir	pleuvr-	to rain
pouvoir	pourr-	can
savoir	saur-	to know
tenir	tiendr-	to hold	maintenir, obtenir, soutenir
valoir	vaudr-	to be worth
venir	viendr-	to come	devenir, parvenir, revenir
voir	verr-	to see	revoir
vouloir	voudr-	to want

express need or obligation

the essential semi-auxiliary verb devoir, which means "must", "have to", or "need to" when placed before another verb.

• Je dois manger plus de légumes. — I must eat more vegetables.
• Ils doivent acheter plus de livres. — They need to buy more books.

Remember that the impersonal expression il faut + infinitive can also express a need or obligation.

• Il faut manger. — It is necessary to eat.
• Il nous faut payer des taxes. — We have to pay taxes.

You can also use the impersonal construction from the last unit, il est + adj + de.

• Il est nécessaire de reprendre le travail. — It is necessary to return to work.
• Il est nécessaire de faire attention. — It is necessary to pay attention.

Another way to express obligation is avoir à, though this is rarely used by French speakers because it tends to create vowel conflicts.

• Je sais ce que j'ai à faire. — I know what I have to do.
• J'ai quelque chose à vous dire urgemment. — I have something to tell you urgently.

What about when you want to say that you need something (instead of having to do something)? One way you learned previously is to use il faut with a noun instead of a verb.

• Il faut du lait. — Milk is needed.
• Il faut un début à tout. — A beginning is needed for everything.

A more common expression for need is avoir besoin de quelque chose. While this literally translates as "to have need of something", a better translation is "to need something".

• J'ai besoin d'un stylo. — I need a pen.
• Il a besoin d'eux. — He needs them.
• Elles ont besoin de magazines en anglais. — They need magazines in English.
• Vous avez besoin de ce produit. — You need this product.

You can also use this expression with verbs.

• Vous avez besoin de gagner plus d'argent. — You need to earn more money.
• Mes amis ont besoin de manger. — My friends need to eat.

Notice that besoin is invariable in this expression, but the noun besoin ("need") is just a standard masculine noun that does have a plural form.

• Il a des besoins importants. — He has important needs.
• Il y a un besoin urgent d'agir. — There is a pressing need to act.

Consider the difference between "I don't have to" and "I must not". The former expresses a lack of obligation, while the latter expresses an obligation to avoid an action. In French, to express a lack of obligation, use a negation with avoir besoin de or avoir à.

• Je n'ai pas besoin d'un stylo. — I don't need a pen.
• Nous n'avons pas besoin de votre permission ! — We don't need your permission!
• Elle n'a pas à parler. — She doesn't have to speak.
• On n'a pas à manger maintenant. — We don't have to eat right now.

To express "must not" in French, use a negation with devoir or il faut.

• Elle ne doit pas manger de poisson. — She must not eat fish.
• Nous ne devons pas nous mentir. — We must not lie to each other.
• Il ne faut pas réfrigérer les tomates. — One must not refrigerate tomatoes.
• Il ne faut jamais oublier les leçons de l'histoire. — We must never forget the lessons of history.

https://www.duolingo.com/skill/fr/Abstract-Objects

Faire vs Rendre

In "Verbs: Present 1", you learned about the causative faire, which can indicate that the subject has directed someone to perform an action. Notice that faire is followed by an infinitive here.

• Je le fais réparer. — I am having it fixed.
• Elle lui a fait perdre 5 kilos. — She made him/her/it lose 5 kilos.
• Je leur ai fait faire de l’exercice. — I made them (get some) exercise.

The verb rendre ("to make") can also indicate that the subject has caused something to happen, but it's used with adjectives instead of verbs.

• Elle le rend heureux. — She makes him happy.
• Ça me rend fou ! — That drives me crazy!
• L'erreur a rendu le texte incomprehensible. — The error rendered the text incomprehensible.

https://www.duolingo.com/skill/fr/Verbs:-Infinitive-2

subjunctive

BampaOwl 

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The six basic endings of the present subjunctive are -e, -es, -e, -ions, -iez, -ent. These are added to a stem which is derived as follows; take the 3rd person plural present indicative, remove the "ent" from the end, then add endings as above.So for boire, you take boivent, so the stem is boiv-, so the subjunctive is je boive.

BUT, quoting from my grammar book, "If the stem of the Present Indicative changes during the tense, the stem of the Present Subjunctive usuallyfollows suit. So for boire, the Present Indicative is bois, bois, boit, buvons, buvez, boivent, and the Present Subjunctive is boive, boives, boive,buvions, buviez, boivent.

Avoir and être are different, as you might expect. And then there's the Imperfect Subjunctive ...

Sitesurf wrote:
... "aimer que" which indeed drives the subjunctive mood in the subordinate clause, as well as the other appreciation verbs: apprécier, adorer, détester, haïr, préférer.

https://www.duolingo.com/comment/16040381$comment_id=16070931

Preposition + infintive

Pour generally marks the purpose, end, or object of an action. Can be translated to "in order to."

For c'est and il est, if it's a dummy subject:
impersonal expression + de + intransitive infinitive
or
impersonal expression + de + transitive infinitive + direct object

If it's a real subject:
impersonal expression + à + intransitive infinitive

http://french.about.com/od/expressions/a/impersonal.htm


the subject in the impersonal construction il est + adjective + de must be a dummy subject. If it's a real subject, you must use à instead of de.
https://www.duolingo.com/skill/fr/Verbs:-Infinitive-2

Passive infinitive follows the form: noun + à + infinitive

http://french.about.com/od/grammar/a/passiveinf.htm

These have different meanings depending on which preposition they use:

http://french.about.com/library/prepositions/bl_prep_a_vs_de2.htm

passé composé (PC)/present perfect.

https://www.duolingo.com/skill/fr/Verbs%3A-Compound-Past

http://www.frenchtoday.com/blog/etre-versus-avoir-french-auxiliary-verbs-past-tenses

Compound verbs contain a conjugated auxiliary and a participle. Most use the avoir conjugated auxiliary verb, but a handful use être. These verbs involve movement or transformation. Here are some: Arriver (arrive), partir (leave), Descendre (descend), monter (ascend), Venir (come), aller (go), devenir (become), revenir (return), Entrer (enter), sortir (leave), rentrer (re-enter), Naître (be born), mourir (die), Tomber (fall), souvenir (remember), raser (shave).

Note that participles vary with gender and number just like adjectives.

A participle that follows avoir is usually invariable. However, if a direct object appears before avoir, its participle agrees with the direct object. A participle that follows être agrees with the subject.

If a pronominal verb is intransitive, then the participle is invariable. Transitive verbs are able to take a direct object like "I saw a donkey." Intransitive verbs are not taking a direct object, e.g., look in look at the sky.

The PC can translate to the preterit (simple past) when it narrates events or states that began and ended in the past.


The PC can also translate to the present perfect for actions and states that started in the past and are still true.

Most past participles are formed by adding an ending to a verb's root, -é to -er verbs, -i to -ir verbs, and -u to -re verbs.

Most irregular verbs have irregular participles.
boire = bu
être = été
lire = lu
venir = (être) venu.
naître = nédevenir = devenu
mourir = mort
mettre = mis

conduire = conduit
disparaître = disparu
permettre = permis
prendre = pris
recevoir = reçu
voir = vu
dire = dit
faire - fait
ouvrir = ouvert
réduire = réduit
savoir = su
avoir = eu

prévoir = prévu

pouvoir = pu

croire = cru

Verbs with different meanings with à and de

Verbs with different meanings with à and de

décider à		to persuade, convince
décider de		to decide to
demander à		to ask (for permission)
demander de		to ask (s.o. to do s.t.*)
jouer à		to play a game or sport
jouer de		to play an instrument
manquer à		to miss someone
manquer de		to neglect (to do s.t.)
(more about manquer)
parler à		to talk to
parler de		to talk about
penser à		to think about (imagine)
penser de		to think about (opinion)
(more about penser)
profiter à		to benefit
profiter de		to make the most of
venir à		to happen to
venir de		to have just (done s.t.)
(more about venir)

 Verbs that use both à and de in the same sentence

conseiller à qqun de faire qqch		advise s.o. to do s.t.
défendre à qqun de faire qqch		forbid s.o. to do s.t.
demander à qqun de faire qqch		ask s.o. to do s.t.
dire à qqun de faire qqch		tell s.o. to do s.t.
interdire à qqun de faire qqch		forbid s.o. to do s.t.
ordonner à qqun de faire qqch		order s.o. to do s.t.
permettre à qqun de faire qqch		allow s.o. to do s.t.
promettre à qqun de faire qqch		promise s.o. to do s.t.
téléphoner à qqun de faire qqch		call s.o. to do s.t.

qqun	quelqu'un		s.o.	someone
qqch	quelque chose		s.t.	something

http://french.about.com/library/prepositions/bl_prep_a_vs_de2.htm

Past Imperfect (imparfait)

You can construct it by taking the present indicative nous form of any verb and replacing the -ons with the imperfect ending -ais -ais -ait -ions -iez -aient.

The only irregular imperfect verb is être, which takes on an ét- root but still follow the imperfect ending.

The imperfect (imparfait) describes situations, states of mind, and habits in the past. In a story, it sets the scene or background; thus, it often translates to and from the English past continuous tense (was/were going) or repeated actions or habits (used to, would).

We can translate using simple past tense for habits such as:

• Nous visitions chaque semaine. — We visited every week.
• À l'époque, elle chantait souvent. — Back then, she often sang.

or for stative verbs (to be, to think, to look, to smell, to understand):

• Il croyait son père. — He believed his father. (Not "was believing".)
• Nous avions trois cousins. — We had three cousins. (Using "were having" would make you a confessed cannibal.)

STATES OR SITUATIONS

To translate, use the English preterit (simple past) here to describe mental or physical conditions, scenes, date or times, weather, etc. (stative verbs).

ACTIONS OR PROCESSES

The continuous past can be used here to set up a scene by describing an action or process.

• Je marchais lentement. — I was walking slowly. 
• Vous regardiez la mer. — You were watching the sea.
• Elles pensaient à leurs enfants. — They were thinking of their children. ("Thinking" is a process here.)

Here are some irregular verbs that we should pay attention to:

ét-: to be. This is special, not forming from its present indicative nous form.

j'étais
tu étais
elle était
nous étions
vous étiez
ils étaient

Aller: to go. The present indicative nous form is nous allons. So the imparfait root is all-. So we have:

J'allais
Tu allais
elle allait
nous allions
vous alliez
ils allaient

Faire: to do, to make. The present indicative nous form is nous faisons. So the imparfait root is fais-.

Je faisais
tu faisais
il faisait
nous faisions
vous faisiez
ells faisaient

Avoir: to have. The present indicative nous form is nous avons. So the imparfait root is av-.

J'avais
tu avais
on avait
nous avions
vous aviez
ils avaient

Conjugating Tenses of Regular Verbs

Blue=Match whole rows for 2; Orange=Match partially; Red = Match for all 3 - learn once, learn for all.

Regular -er Verb Endings

Tense (stem)	je	tu	il/elle/on	nous	vous	ils/elles
Present (parl)	-e	-es	-e	-ons	-ez	-ent
Simple Past(parl)	-ai	-as	-a	-âmes	-âtes	-èrent
Imperfect (nous parl-)	-ais	-ais	-ait	-ions	-iez	-aient
Future (infinitive parler)	-ai	-as	-a	-ons	-ez	-ont
Conditional (infi. parler)	-ais	-ais	-ait	-ions	-iez	-aient
Subjunctive (ils parl-)	-e	-es	-e	-ions	-iez	-ent

Regular -ir Verb Endings

Tense (stem)	je	tu	il/elle/on	nous	vous	ils/elles
Present (fini)	-s	-s	-t	-ssons	-ssez	-ssent
Simple Past(fin)	-is	-is	-it	-îmes	-îtes	-irent
Imperfect (finiss)	-ais	-ais	-ait	-ions	-iez	-aient
Future (finir)	-ai	-as	-a	-ons	-ez	-ont
Conditional (finir)	-ais	-ais	-ait	-ions	-iez	-aient
Subjunctive (finiss)	-e	-es	-e	-ions	-iez	-ent

Regular -re Verb Endings

Tense (stem)	je	tu	il/elle/on	nous	vous	ils/elles
Present (vend)	-s	-s	(nothing)	-ons	-ez	-ent
Simple Past(vend)	-is	-is	-it	-îmes	-îtes	-irent
Imperfect (vend)	-ais	-ais	-ait	-ions	-iez	-aient
Future (vendr)	-ai	-as	-a	-ons	-ez	-ont
Conditional (vendr)	-ais	-ais	-ait	-ions	-iez	-aient
Subjunctive (vend)	-e	-es	-e	-ions	-iez	-ent

http://www.dummies.com/how-to/content/french-verbs-for-dummies-cheat-sheet.html

être + noun (no article)

Sitesurf 

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A few nouns describing people can also work the same way: elle est témoin de..., il est victime de..., ils sont élèves..., elles sont championnes...

https://www.duolingo.com/comment/14219021$comment_id=14222337

Sitesurf 

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"nous sommes frères" and "ils sont frères" are identical in construction, where "frères" works as an adjective.

"nous sommes des frères" is not impossible, "frères" is a noun and "des" is the plural indefinite article. In singular, you can say "je suis un frère de XX", meaning that XX has at least one other brother.

"ils sont des frères" is grammatically incorrect, because "ils sont + modified noun" automatically turns to "ce sont + modified noun". (Reminder: a modifier can be an article, a demonstrative or possessive adjective, a number).

"Ce sont frères" does not work either and this is why I pointed to "ils sont frères" or "ce sont des frères" and not "ils sont des frères".

These constructions are specific to the verb "être", so they do not apply to the verb "avoir": j'ai un frère, j'ai des frères.

I gave you other nouns acting as adjectives on another thread, but again this is unique to the verb "être" (or "devenir" or "rester"): un témoin, une victime, un(e) élève, un champion...

https://www.duolingo.com/comment/14220971$comment_id=14222310

reflexive verbs keep reflexive pronouns

Sitesurf 

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[For the negative,] In the imperative mood, the subject disappears. However, reflexive verbs keep their reflexive pronoun:

• n'écoute pas ! n'écoutons pas ! n'écoutez pas !
• ne t'inquiète pas ! ne nous inquiétons pas ! ne vous inquiétez pas !

https://www.duolingo.com/comment/13840748$comment_id=13869707

imparfait

Sitesurf 

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The "imparfait" tense suggests a certain duration in the past, that is generally translated with the continuous preterit, so the right translation should be "he was not doing anything".

""He did not do anything" translates in "il n'a rien fait".

___

Other notes:

il ne faisait rien (depuis des mois) = he had not been doing anything (for months).

Il ne fait rien = He does nothing

Il n'a fait rien = he didn't do anything 

il ne faisait rien = He was not doing anything

ce n'était rien = it was nothing

cela ne faisait rien = Nothing mattered/that did not do anything

Il faisait tout = he used to do/make everything