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Usage of the Past Anterior 
- The past anterior is used for actions completely terminated before the main past action. It translates as to have done something (before doing something else). Ex: I had gone to the store before I picked him up.
Formation of the Past Anterior 
- The past anterior is a compound tense- it consists of two verbs, the auxiliary verb and the past participle one seeks to use in this tense.
- The auxiliary verb is conjugated as if it were being used in the passé simple.
- The past participle is added immediately after the auxiliary verb.
- A negative structure such as ne ... pas is always placed around the auxiliary verb, not the past participle.