Knowing how long the test would last, the students who finished back and waited until the end of the exam.
A. settle
B. settled
C. settling
D. to settle
网友回答
A. settle
(答案→)B. settled
C. settling
D. to settle
解析：该题考查句子结构。学生易犯思维定势的错误而选C，其实who finished是定语从句，该处缺谓语动词。