819. (_a._) Verbs in #-ere# have rarely forms of verbs in #-ēre# in the
present system: as, #abnueō#, _nod no_, #abnuēbunt# (Enn.), for #abnuō#,
#abnuent#; #congruēre#, _to agree_ (Ter.), for #congruere#. For verbs in
#-iō#, #-ere# (or #-ior#, #-ī#), with forms of verbs in #-īre#
(or #-īrī#), see 791. Once #pīnsībant# (Enn.).
820. (_b._) Some verbs in #-āre# have occasionally a present stem like
verbs in #-ere#: as, #lavis#, _washest_, #lavit#, &c., for #lavās#,
#lavat#, &c.; #sonit#, _sounds_, #sonunt#, for #sonat#, #sonant#. Others
have occasionally a present stem like verbs in #-ēre#: as, _dēnseō_,
_thicken_, _dēnsērī_, for _dēnsō_, #dēnsārī#.
821. (_c._) Some verbs in #-ēre# have occasionally a present stem like
verbs in #-ere#: as, #fervit#, _boils_, #fervont#, for #fervet#,
#fervent#. See also #fulgeō#, #oleō#, #scateō#, #strīdeō#, #tergeō#,
#tueor# in the dictionary. #cieō#, _set a going_, sometimes has a
present stem in #-īre#, particularly in compounds: as, #cīmus#, #ciunt#,
for #ciēmus#, #cient#.
822. (_d._) Some verbs in #-īre# have occasionally a present stem like
verbs in #-ere#: as, #ēvenunt#, _turn out_, for #ēveniunt#; #ēvenat#,
#ēvenant#, for #ēveniat#, #ēveniant#, and #advenat#, #pervenat#, for
#adveniat#, #perveniat# (Plaut.).