These problems, , will seriously affect the growth of teenagers and even the nation’s future.
A. solved properly
B. if solved properly
C. not if properly solved
D. if not solved properly
网友回答
A. solved properly
B. if solved properly
C. not if properly solved
(答案→)D. if not solved properly
解析：考查状语从句的省略。if not solved properly，if后省略了they are 。