Theoldcouplewalkedratherslowly,andcouldbeseen,fromtime...

問題詳情：

 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

知識點：非謂語動詞

題型：選擇題