Theoldcouplewalkedratherslowly,andcouldbeseen,fromtimet...

问题详情：

The old couple walked rather slowly, and could be seen, from time to time, to stop and rest, ______ out to sea.

A. to be staring               B. stared               C. having stared            D. staring

【回答】

D

知识点：非谓语动词

题型：选择题