Desservir is a french third group verb. So, this verb is irregular and do not follow a regular conjugation pattern like first or second group verbs. Follow this link to see all the endings of the conjugation of most of the third group verbs :
conjugation rules and endings for the second group verbs.
Desservir verb is conjugated in negative form. The placement of the negative adverb follow the following rules:
- the adverb
« ne » is placed after the pronoun and before the verb.
- in simple tenses, the adverbs (
« ne ...pas »,
« ne...plus »,
« ne...jamais », etc...) surround the verb
desservir.
- in compound tenses or in ive voice, the negative adverbs surround the auxiliary.