—Why do you look sad?
—There are so many problems ________.
A.remaining to settle
B.remained settling
C.remaining to be settled
D.remained to be settled
答案:C
由于remain是不及物动词,故应用现在分词remaining,相当于定语从句that remains;动词settle置于remain之后,应用动词不定式的被动结构来表示动作还未完成。