💡 Detailed Explanation
Translation: Mr. Kimura is good at tennis, isn't he? I'm envious.
- Grammatical point: Adjectival noun ending before 'ですね'.
- Explanation: 'じょうず' (上手 / na-adjective) can end a sentence politely when followed directly by 'ですね' (without needing 'だ' in spoken/polite mixed N5 levels, as 'じょうずですね' is the direct and natural polite formulation). 'じょうずだ' is plain and sounds unnatural when directly combined with 'ですね' in this textbook context. 'じょうずに' is adverbial.