These problems may lead to more serious ones if ___unsolved.A.making B.remained C.keeping D.left
问题描述：
These problems may lead to more serious ones if ___unsolved.A.making B.remained C.keeping D.left
These problems may lead to more serious ones if ___unsolved.
A.making B.remained C.keeping D.left
答
首先if后有省略,问题是被留下没解决,排A C
B是不及物动词,没有被动,因此选D