问题
选择题
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
答案
答案：B
句意：他忙着编故事，偶尔停下来吸只烟。此题容易错选A。但only to do 表结果，人、而根据题意可知，此处表伴随且stop 几乎与was busy 同时发生，故用B，而having stopped 表示此动作限于谓语动词发生，与题意明显不符。