The past stem in Persian is simply formed by removing “an” from the end of the infinitive. Then, personal endings are added to this stem. For example, for the verb ‘to laugh,’ remove ‘an’ from the infinitive خندیدن xandidan to make خندید xandid “He laughed,” and then add the first person singular ending م to make خندیدم xandidam
“I laughed.” The past tense third-person singular does not have an ending. Hence, “He laughed” is the same as the past stem خندید xandid.

The personal endings in the past tense are as follows:

Unlike in English, in Persian, when in a single sentence or two or more dependent clauses in the past tense more than one verb is incorporated, the first verb sets the tense (in the past) and the rest of the verbs are invariably in the present tense. For example:

متوجّه شدم که او در خانه نیست
motevajjeh šodam ke u dar xāne nist
“I realized that he/she was not at home.”

به من گفت که خسته است
be man goft ke xaste ast
“S/he told me that s/he was tired.”

به من گفت که او را ندیده است
be man goft ke u rā nadide ast
“S/he told me that s/he had not seen him/her.”

باید می‌فهمیدم که او در آبادان خوشحال است
bāyad mi fahmidam ke u dar ābādān xošhāl ast
“I should have realized that s/he was happy in Abadan.”