Know-it-all?

One of my private students, Tokijiro, is a 78 year old psychiatrist.
He is a graceful, sophisticated, smart gentleman.

However, his problem is...he wants to know EVERYTHING.
I go over just for a few pages of the textbook in a 50-minute class because of a shower of his questions.
For example;

Keiko: So, while she was having a coffee at the Starbucks...
Toki: Wait a minute. What does "Starbucks" mean?

Keiko: In this exercise, let's act it out..
Toki: Excuse me. Why do you say "act it OUT?" What does "out" mean?

Keiko: The pronunciation difference between "blink" and "brink..."
Toki: Brink? What's the meaning difference between "brink" and "cliff???"

...I always want to say, "What do you need?? You should PRACTICE first before asking so many questions!!!"
But surely, never do I. I know he has never reviewed & previewed. He just enjoys asking questions at my school. (In another words. he enjoys satisfying a thirst for knowledge?)

Today, he asked me as usual.
Toki: "What's the real name of "a.m?" What does it come from??"
Keiko: Well... "after midnight."
Toshi: Wow! Really? So, how about "p.m?"
Keiko: Ah..."pre midnight."
Toshi: I didn't know that!

...After the class, I looked them up.
My dictionary said, "a.m" is the abbreviation of "ante meridium." "P.M." is "post meridian." They are not English, Latin!
It's obvious I lied to my student!
...But I may not correct. He doesn't have to know Latin!!!
Sometimes, a teacher should pretend to be a know-it-all...