GMAT语法全解中的一道题，关于where引导的状语从句，请教NN哦

我这里恰好有个例句：
What he likes best about painting is its contrast to opera, where the challenge is to use one's talents to bring to life the works of others.
这句中，where指代了 opera, 而opera 不是一个表示实实在在地点的名词。但这里where 用的最恰当。

还有个句子。
Now the tide appears to be turning. As personal iujury claims continue as before, some courts are beginning to side with defendants, especially in cases where a warning label probably wouldn't have changed anything.
这句话中，我觉得除了where 外，没有其他词可以指代cases 了。

以上类似的例句还有很多，我看就不需要一一列举了吧。