Fill in with the right option: I _________ him for a long time.

Correct answer: have known

Explanation: Here we use the Present Perfect Tense (have/has + past participle) to show an action that started in the past and continues up to the present. Words like “for” and “since” usually signal the need for this tense. have known ✅ – correct; it shows the speaker started knowing him long ago and still knows him. knew ❌ – simple past; it suggests the action ended in the past. had known ❌ – past perfect; used only when referring to two past actions (not the case here). should have known ❌ – modal perfect; expresses regret, not continuity. ✔️ Correct sentence: I have known him for a long time.✅