I was about to leave the office the telephone rang．So I stopped it．
A. when; to answer
B. when; to reply
C. while; answering
D. as; replying
网友回答
A. when; to answer
(答案→)B. when; to reply
C. while; answering
D. as; replying
解析：考查短语搭配。be about to do sth. when...是固定搭配,正要做某事时,....发生了；stop to do停下来做。句意：我正要离开办公室的时候，突然电话响了。因此我停下来接它。