A discussion with a kind professor

After my presentation was done, a professor gave me a lot of comment regarding every slide I showed. I really appreciate for his passionate suggestions. I visited his office today, and talked about some aspects of my study that had been indicated by him. He gave me his time for one hour to discuss my research. It was wonderful time. I don't know why he was so kind to me. I regret that I didn't have the enough English skill to show my gratitude to him.