题目

 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 答案：.B 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。用分液漏斗可以分离的一组液体混合物是(　　)。A.溴和CCl4 B.苯和溴苯C.硝基苯和水 D.汽油和苯