The part of the grammar page this lesson drills — read it here, then use it.
Making the participle
Take the infinitive, drop -ти, and add the ending - -о for a male subject, -ла for female, -ло for neuter; see the table below. Nearly every verb you have met so far works this way.
In the plural: -ли for men or a mixed group, -ле for a group of women, -ла for neuter things. A mixed group always takes the masculine -ли, even if only one man is present.
The participle agrees with the subject
The ending is chosen by who or what the subject is, not by the person speaking to you. Ана је читала and Марко је читао use the same auxiliary је and differ only in the participle - the part that carries the gender.
This includes ја and ти, which have no gender of their own: a woman says ја сам радила and a man ја сам радио - the sentence itself reveals who is speaking.
Saying it did not happen
The negative uses the fused forms you already know from бити - нисам, ниси, није, нисмо, нисте, нису - followed by the same participle. Нисам радио means “I did not work”; there is no separate не here, exactly as in the present tense.
To ask a question, put да ли in front and leave the rest alone: Да ли си радио? Word order doesn't change - same rule as in the present tense.
| Subject | Ending | Form |
|---|---|---|
| muški rod | -o | radio |
| ženski rod | -la | radila |
| srednji rod | -lo | radilo |
| muški rod, množina | -li | radili |
| ženski rod, množina | -le | radile |
| srednji rod, množina | -la | radila |