These problems， will seriously affect the growth of teenagers and even the nation's future.
A. not if solved properly
B. if solved properly
C. not if properly solved
D. if not solved properly
网友回答
A. not if solved properly
B. if solved properly
C. not if properly solved
(答案→)D. if not solved properly
解析：句意：这些问题如果不被恰当解决将会严重影响青少年的成长甚至国家的未来。if not solved properly是if they are not solved properly的省略形式。当主、从句的主语一致，且从句中谓语为be时，可省略从句中的主语和动词be。