Use of the imperfect
     To describe a situation or habitual action in the past, use the imperfect.

Formation of the imperfect
     All French imperfects (with the single exception of être) are formed regularly off the stem of the first person plural (the "nous" form) less the ending -ons, to which you add the endings -ais, -ais, -ait, -ions, -iez, -aient.
     So the imperfect of parler would be: nous parlons > parl--ons> parl--> je parlais, tu parlais, etc.
     The imperfect of finir would be: nous finissons> finiss--ons> finiss--> je finissais, tu finissais, etc.
     The imperfect of rendre would be: nous rendons > rend--ons> rend--> je rendais, tu rendais, etc.

     Even irregular verbs are regular in the imperfect. For example, j'avais (nous av--ons), tu faisais (nous fais--ons), il allait (nous all--ons), nous disions (nous dis--ons), vous buviez (nous buv---ons), elles venaient (nous ven--ons).

     Etre has the only irregular imperfect stem, ét--. So the imperfect would be J'étais, tu étais, etc.



Interrogative pronouns
     Some French equivalents of who? and whom? are:
     qui/qui est-ce qui for pronoun subjects of verbs. So: qui parle/qui est-ce qui parle? = Who is talking?.
     Qui? (with an inverted verb)/qui est-ce que? (without an inverted verb) for objects of a verb. So: Qui voyez-vous/Qui est-ce que vous voyez? = Who(m) do you see?
     Qui? (with an inverted verb)/qui est-ce que? (without an inverted verb) for objects of a preposition. So: A qui parlez-vous?/A qui est-ce que vous parlez? = Who[m] are you talking to?

Some French equivalents of what? are:
     Qu'est-ce qui for subjects of verbs. So: Qu'est-ce qui se passe? = What's happening?
     Que/ (with an inverted verb)/Qu'est-ce que (with a verb that isn't inverted). So: Que voudriez-vous?/Qu'est-ce que vous voudriez? = What would you like?
     quoi (with an inverted verb), quoi est-ce que (with a verb that isn't inverted) after a preposition. So: A quoi pensez-vous?/A quoi est-ce que vous pensez? = What are you thinking about?