These are
the dictionary entries for verbs.
Verbs belong
to 1st, 2nd, 3rd, or 4th
conjugation.
If the
second principal part, the infinitive
(to____) ends in “āre” then the verb belongs to 1st
conjugation.
If the
second principal part, the infinitive
(to____) ends in “ēre” then the verb belongs to 2nd conjugation.
moneō monēre monuī monitus-a-um   warn, advise
If the
second principal part, the infinitive
(to____) ends in “ere” then the verb
belongs to 3rd  conjugation.
dūcō dūcere dūxī ductus-a-um  lead   
If the
second principal part, the infinitive
(to____) ends in “īre” then the verb belongs to 4th
conjugation.
audiō audīre audīvī audītus-a-um   hear or listen to
audiō audīre audīvī audītus-a-um   hear or listen to