Generally, the indicative prefixes 'ta-' to the subject prefix except for the first person singular which changes to 'nshi' or 'shi'. Generally, the subjunctive adds 'i' after the pronoun prefixes and in most cases changes a final 'e' to 'a'. The infinitive occasionally uses the negative 'te'. However, the precise rules are more complex, and the forms depend more finely on tense, aspect and mood. When the negative is used with the imperfect 'le', it is often in the sense of action not yet done, and is referred to by Schoeffer as a separate 'deferred tense'.