--- Hello! Is Mr. John in the office?

--- Yes. But I’m sorry. He is busy _________ and can’t speak to you.

--- Hello! Is Mr. John in the office?

--- Yes. But I’m sorry. He is busy _________ and can’t speak to you.

1. A.
   at once
2. B.
   at present
3. C.
   at the end
4. D.
   at first

—Hello! Is Mr. John in the office?

—Yes. But I’m sorry. He is busy _____ and can’t speak to you.

A. at once　　　　　　　　　　　　　 B. at present　　　　

C. at the end　　　　　　　　 D. at first

--- Hello! Is Mr. John in the office?
--- Yes. But I’m sorry. He is busy _________ and can’t speak to you.