He had been so absorbed watching the car passing by that he didn’t notice his friends .
A. to; ing
B. in; to e
C. on; ing
D. in; ing
网友回答
A. to; ing
B. in; to e
C. on; ing
(答案→)D. in; ing
解析：考查固定结构。Be absorbed in doing sth，全神贯注于……；notice sb doing sth.注意到某人正在做某事。所以选D。