Crack the Verb Code!

REVIEW [read carefully! :)]
There are 4 families of verbs we have learned, called conjugations.
The FIRST is marked by -ā- at the end of the verb stem, like cantat (cantā-) and plōrat (plōrā-).
The SECOND is marked by -ē- at the end of the verb stem, like tenet (tenē-) and ridet (ridē-).
The FOURTH is marked by -ī- at the end of the verb stem, like venit (venī-) and audit (audī-).
The THIRD is funky. We can think of it as having no vowel to mark it, and its vowel changes between -e- and -i- and -u-. Carpit and agit are third conjugation verbs.

INDICATIVE = statements of fact.

3rd person singular: add -t to the verb stem (this person marker makes the vowel before it short). Add -it to the third conjugation. Cantat. Tenet. Carpit. Audit.

3rd person plural add -nt to the verb stem (this person marker makes the vowel before it short). Add -unt to the third conjugation, -iunt to the fourth conjugation. Cantant. Tenent. Carpunt. Audiunt.

IMPERATIVE = command.

2nd person singular: the stem of the verb. For the third conjugation, add -e. Cantā! Tenē! Carpe! Audī!

2nd person plural: add -te to the stem. For the third conjugation, add -ite. Cantāte! Tenēte! Carpite! Audīte!