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

问题补充：

--- 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

答案：

A. at once

(答案→)B. at present

C. at the end

D. at first

解析：词义辨析。A立刻，马上；B现在；C最后；D起初。句意：—你好，Mr John在办公室吗？—是的。但是对不起。他现在很忙，没有时间和你说话。故B正确。