[825.] The sign for the variable vowel is -o|e-: thus, rego|e-, which may be read ‘rego- or rege-,’ represents rego- or regu-, rege- or regi-, as seen in rego-r or regu-nt, rege-re or regi-t.
[826.] The variable vowel occurs in the present of verbs in -ere, except in the subjunctive, in the future in -bō or -bor, and in the future perfect, as may be seen in the paradigms. It is usually short; but in the active, o is long: as, regō, laudābō, laudāverō; and poets rarely lengthen i in the second and third person singular of the present. For the future perfect, see [882].
[827.] In old Latin, the stem vowel of the third person plural of the present was o: as, COSENTIONT; o was long retained after v, u, or qu ([107, c]): as, vīvont, ruont, sequontur; or, if o was not retained, qu became c: as, secuntur.
[I. THE PRESENT SYSTEM.]
I. Primitives.
(A.) ROOT VERBS.
[828.] A root without addition is used as the present stem, in the present tense or parts of the present tense, in root verbs ([744-781]): as,
es-t, is; da-t, gives; inqui-t, quoth he; i-t, goes; nequi-t, can’t; ēs-t, eats; vol-t, will; fer-t, carries. With reduplicated root ([189]): bibi-t, drinks; seri-t, sows; sisti-t, sets.
(B.) VERBS IN -ere.