Question

【题目】This problem may lead to more serious ones if ________ unsolved.

A. making B. remained C. keep D. left

Answer 1

【答案】D

【解析】句意：如果这个问题仍然未被解决，将会导致更严重的问题。只有left和remain可以表示“剩下的”；条件从句是省略句，省略了主语和be动词，还原应为the problem is left unsolved. B项remain为不及物动词，不能用被动形式。故选D。