---Why do you look so upset?
---There are so many troublesome problems .
A. remaining to be settled
B. remained settled
C. remaining to settle
D. remained to be settled
网友回答
(答案→)A. remaining to be settled
B. remained settled
C. remaining to settle
D. remained to be settled
解析：考察非谓语动词。根据句子结构可知，该处为problems的定语，remain是系动词，无被动。故排除BD. Remain的用法是sth remain to be done，
句意为，有很多麻烦的问题留待解决。