The past tense base form is made by removing the ن from the end of the infinitive.
For Example: کردن means to do
Past Tense base form is کرد
Adding a personal ending to the past tense base form shows who or what is performing the action. Eg: he/she/it.
* 3rd person singular has no personal ending when the verb is in past tense (‘He did’).
Negative form - is formed by adding na- ( ن ) to the beginning of all the verb tenses including the Infinitive form.
‘Not to do’ - past tense
Other Examples
nadāshtam نَداشتم (I did not have)
nabudid نَبوديد (you were not)
If the present stem begins with آ the negative prefix is pronounced ' nai '
Example: نیامدم I did not come
Supplementary Exercise 13 shows the conjugation of some commonly used Persian infinitives with the verbal endings for your reference. To go to this exercise click here.