He _______ (finish) his homework before dinner yesterday. He _______ (finish) his homework already.

Key Concept: Past Simple vs. Present Perfect

The Past Simple is used for completed actions at a specific time in the past. The Present Perfect is used for actions that have a result in the present or are connected to the present. Words like 'already', 'yet', 'just', 'ever', 'never' are commonly used with the Present Perfect. 'Yesterday' clearly indicates the Past Simple.

Solution:

• He finished his homework before dinner yesterday. (Specific past time)
• He has finished his homework already. (The completion of the homework has a present relevance - he doesn't need to do it now.)

Answer: finished, has finished