1. They will fly to South Africa, ______ they plan to stay for half a month.
A. when B. where C. there D. which
【答案】B
【解析】
【分析】
【详解】考查定语从句。句意：他们将飞往南非，计划在那里停留半个月。分析句子可知，空后面的句子为非限定性定语从句，修饰先行词South Africa，关系词在从句中作地点状语。故选B。
2. ________ is often the case with children, Tom was better by the time the doctor arrived.
A. It B. That C. What D. As
【答案】D
【解析】
【分析】
【详解】考查定语从句。句意：汤姆在医生赶到前已经完全没事了，这种事经常发生在孩子身上。as 引导非限制定语从句，先行词是整个句子，as在从句中作主语，意为“正如，像……一样”。故选D。
【点睛】as可以引导非限制性定语从句，可以放在句首或句末，意为“正如”，指代主句的内容，在从句中可做主语，宾语和表语。有些固定搭配可记忆，如：as is often the case；as is know to all等。
3. The reason ________ he explained was________ he was ill and unable to go to school.
A. which; that B. why; because C. which; because D. why; that
【答案】A
【解析】
【详解】考查定语从句和表语从句。句意：他解释的原因是他生病了，不能去上学。第一空为限定性定语从句，修饰先行词reason，且先行词在从句中作宾语，指物，应用关系代词which/that；第二空为表语从句，从句中不缺少成分，句意完整，应用只起连接作用的that。故选A。
