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
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
B
句意为他在忙着写一个故事，只是偶尔停下来抽支烟。此处应为现在分词短语作伴随状语，表示与write伴随的动作。A项通常作目的状语和结果状语。