He was busy writing a story, only once in a while to smoke a cigarette.
A. to stop
B. stopping
C. to have stopped
D. having stopped
网友回答
A. to stop
(答案→)B. stopping
C. to have stopped
D. having stopped
解析：考查分词做状语。本题中的动词stop与句子的主语he构成主动的关系，故使用现在分词的形式。根据句意说明现在动词的动作和句子谓语动词的动作是同时发生的，故使用现在分词的一般式即可。句意：他忙于写小说，只是偶尔停下来抽支烟。故B正确。