BBC news 2010-12-11 加文本

1.The silk Cavalry flag was carried into the 1876 battle at Little Bighorn, where General Custer led 200 soldiers against a much stronger force from the Lakota Sioux and Cheyenne tribes.

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)