问题补充：
单选题Afterseveralyearsofobservation,theresearchgroup______theconclusionthatlanguageacquisitionisfasterwhenstudents______tothesituationwhereitisspoken.A.has come to; exposeB.have arrived at; are exposedC.has concluded; are exposedD.have reached; expose
答案：
B解析试题分析：考查固定短语，arrive at the conclusion意思“得出结论”，be exposed to意思“面对”，come to意思“共计”， concluded意思“结束”， have reached意思“到达”，句子意思“经过几年的观察，研究小组得出当学生面对说语言情况时，语言获得是最快的结论”，所以选B考点：考查固定短语点评：注意句子he research group have arrived at the conclusion that language acquisition is faster when students are exposed to the situation where it is spoken.是个复合句，含有两个定语从句，和一个时间状语从句，the conclusion that language acquisition is faster，先行词是the conclusion，从句hat language acquisition is faster，引导词是关系代词that；when引导的时间状语从句，句子the situation where it is spoken.先行词是the situation，引导词是关系副词where。
