______ the days he had spent with his American friends, he couldn’t help______.
A.Keeping up; smile
B.Staying up; smiling
C.Looking back on; smiling
D.Looking at; to smile
网友回答
C解析考查非谓语动词，第一空考查现在分词作状语，用Looking back on回顾，第二空考查现在分词作宾语，can’t help doing情不自禁作某事，句意：回顾他与美国朋友在一起的那些日子，他情不自禁笑了。所以选C。