答案如下：
Betty won a prize that she had participated in a competition for students on story writing in Chinese .
第一个老兄回答错了.
betty won a prize that is acknowledged by many authorithies in mathmatics.
这句话是定语从句,不是同位语从句.
同位语从句中的that 在句中不充当任何成分.很明显,在这个句中,that 充当了主语.
可以跟同位语从句的名词通常有news,idea,fact,promise,question,doubt,thought,hope,message,suggestion,words（消息）,possibility等.
而这些名词都被称为先行词.该句中的先行词是prize.
先行词要与后面的同位语从句挂钩,也就是两者意思一样.
如：
I can’t stand the terrible noise ____ she is crying loudly.
A.it B.which C.this D.that
析：答案为D.she is crying loudly是the terrible noise的内容,且the terrible noise不在从句中作成分,所以该句为同位语从句.
而下面这句是定语从句：
She heard a terrible noise,____ brought her heart into her mouth.（MET91）
A.it B.which C.this D.that
析：答案为B.分析语境含义、句子结构和句子成分可知,该句为非限制性定语从句,先行词为a terrible noise,且它在从句中作主语.