มูลค่าสูงสุดที่ Christer Tornell ให้เมื่อ Trine Dehli Cleve ให้ 9 คืออะไร?
What was the maximum value that Christer Tornell gave when Trine Dehli Cleve gave a 9?
df = pd.DataFrame(columns=['christer_tornell', 'trine_dehli_cleve'])
df[df['trine_dehli_cleve'] == 9]['christer_tornell'].max()