the good old days，he couldn’t help smiling.
A. Looking back at
B. Looking on
C. Looking forward to
D. Looking into
网友回答
(答案→)A. Looking back at
B. Looking on
C. Looking forward to
D. Looking into
解析：句意：回顾过去美好的日子，他禁不住笑了。Look back at 回顾；Look on仰望；Look forward to 盼望，期望；Look into 向里看。根据题意可知A正确。
考点: 考查动词短语的用法辨析。