C
考查remain用法。Remaining剩下的；sth remain to be done某事有待于被做；本题是两个用法相结合形成remaining to be settled修饰problems.
--- Why do you look sad?
C
考查remain用法。Remaining剩下的；sth remain to be done某事有待于被做；本题是两个用法相结合形成remaining to be settled修饰problems.