强调句是强调句子的某个成分（主语、谓语、宾语、状语......）itis...that...ItisMarythatboughtthebookyesterday.定语从句是修饰名词（主语、宾语、同位语......）的从句Maryboughtabookthatisveryinteresting玛丽买了一本非常有趣的书
