Questions & Answers about Я порекомендовал коллеге новый проект.
Why is "коллеге" in the Dative case here without a preposition?
Verbs of assistance, advising, and recommending (like порекомендовать) take the Dative case for the person receiving the help or advice. You do not need a preposition like the English word "to"; the Dative case ending itself shows who is receiving the recommendation.
Does the ending of "коллеге" change depending on whether the colleague is a man or a woman?
No. Коллега is a common-gender noun, meaning it can refer to either a man or a woman. However, because it ends in -а in its dictionary form, it always follows the feminine declension pattern. The Dative ending will always be -е, regardless of the person's actual gender.
Why does "новый проект" look like it is in the Nominative case?
It is actually in the Accusative case because it is the direct object being recommended. However, because проект is a masculine inanimate noun (a non-living thing), its Accusative form and its matching adjective (новый) look exactly identical to their Nominative forms.
Why use the perfective verb "порекомендовал" here instead of the imperfective?
The perfective form is used because the recommendation was a single, completed action. The speaker is focusing on the result (the colleague has now received the recommendation) rather than describing an ongoing or repeated process.