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2.The issue of team orders caused controversy this year when Ferrari apparently ordered Felipe Massa to let his teammate Fernando Alonso overtake him at the German Grand Prix.
以上两个句子都是由where和when引导的定语从句。
定语从句就其与先行词的关系而言，可分为限定性定语从句和非限定性定语从句。限定性定语从句和先行词之间没有逗号，表示对先行词起修
饰限制作用；而非限定性定语从句和先行词之间有逗号分开，是对先行词进行补充说明，相当于并列句。如：
He is the man who has strong personality. 他是个个性很强的人。（限定性定语从句）
My brother, who works abroad, is coming next week. 我哥哥在国外工作，他下周将回来。（非限定性定语从句）
注：1. 非限定性定语从句不能用that来引导，一般用which，as或who（指人）。用which或as引导时，既可以修饰主句的部分内容，也可修饰主句的全部内容。如：
He spoke confidently, which impressed me most. （which指代整个主句，在从句中作主语）
2. as引导的非限定性定语从句既可以放在主句之前，也可以放在主句之后，但which或who引导的非限定性定语从句不能放在主句之前。如：
As we all know, the moon is a satellite of the earth.
The large area is covered with thick snow, which affects people's life greatly.
3. 在限定性定语从句中，关系代词作宾语时可以省略；但在非限定性定语从句中，关系代词作宾语时不能省略。如：
The film (which) I saw last night is about a young teacher. (which可以省去)
She introduced me to her husband, whom I hadn’t met before. (whom不能省去)
