Language/Italian/Grammar/Do-and-Say

The Italian verbs fare (to do) and dire (to say) are closely related to each other due to their similar irregular conjugation pattern.

Their infinitive form endings may suggest they belong respectively to first (-are) and third (-ire) conjugation. Actually these two verbs are classifiable as second conjugation (-ere) further to their respective Latin stems facĕre and dicĕre. As shown in table below, the original Latin stems fac* and dic* act as base form to which we will add the present tense endings:

P R E S E N T T E N S E
Fare	Prononciation	Dire	Prononciation
Io faccio*	['Io 'faʧ:o]	Io dico	['Io 'diko]
Tu fai	[Tu 'fai̯]	Tu dici	[Tu 'diʧi]
Egli fa	['Eʎʎi fa]	Egli dice	['Eʎʎi 'diʧe]
Noi facciamo*	[ˈNoi̯ fa'tʧamo]	Noi diciamo	[ˈNoi̯ di'ʧamo]
Voi fate	[ˈVoi̯ 'fate]	Voi dite	[ˈVoi̯ 'dite]
Essi fanno	['Essi 'fanno]	Essi dicono	['Essi 'dikono]

Remarks:

* The 1st singular and plural person of fare double the stem consonant -c when taking the personal ending. As a consequence, the prononciation of the sound will be stronger.

The second-decletion stems fac* and dic* act as a base form in the imperfect tense as well:

I M P E R F E C T T E N S E
Fare	Prononciation	Dire	Prononciation
Io facevo	['Io faʧ'evo]	Io dicevo	['Io diʧ'evo]
Tu facevi	[Tu faʧ'evi]	Tu dicevi	[Tu diʧ'evi]
Egli faceva	['Eʎʎi faʧ'eva]	Egli diceva	['Eʎʎi diʧ'eva]
Noi facevamo	[ˈNoi̯ faʧe'vamo]	Noi dicevamo	[ˈNoi̯ diʧe'vamo]
Voi facevate	[ˈVoi̯ faʧe'vate]	Voi dicevate	[ˈVoi̯ diʧe'vate]
Essi facevano	[ˈEssi fa'ʧevano]	Essi dicevano	[ˈEssi di'ʧevano]

The stems fac* and dic* act as base item for past participle as well, thoug they undergo partial modication as an effect of regressive assimilation produced by sound -t.

fac* + -t (past participle particle) => fatt*

dic* + -t (past participle particle) => dett* (stem vowel change follows as well)