______ in the fields on a March afternoon, he could feel the warmth of spring.
A、To walk.
B、Walking
C、Walked
D、Having walked
【正确答案】：B
【题目解析】：本题考查非谓语动词。选项B. Walking在这里是现在分词短语用状语，表示时间，相当于While he was walking in the fields on a March afternoon。选项A.To walk不定式放在句首一般作目的状语；选项C. Walked表示被动，此处句子主语he与动词walk之间是主动关系；选项D. Having walked是现在分词的完成式作状语，表示的动作发生在主句的谓语动词（feel the warmth of spring）之前，显然不合题意。
