There is a long novel （which was written by an American writer Dan brown).
请问各位老师，括号1是后置定语吗？可否改为which called the Da Vinci code吗？假如可以的话，那样前置词novel 就有两个定语从句了吧？
括号里是过去分词短语作后置定语，可以改为关系分句。章振邦书中称一个先行项后带的两个关系分句为“双重关系分句”。双重关系分句分两种状况（见下文）。
网友的的句子改为关系分句：
Thereis a long novel which is called the Da Vinci Code which was written by anAmerican writer Dan brown.
其中，第一个关系分句 which is called the Da Vinci Code 修饰 along novel，第二个关系分句 which was written by an Americanwriter Dan brown 修饰 a long novel which is called the Da Vinci Code。应该注意第二个关系分句的先行项不是a long novel，而是它与第一个关系分句整体作先行项。这样的情况下，两个关系分句处于不同层次。
另一种状况是两个关系分句由并列连词连接，处于同一层次：
You’lleasily find us; just look for a house whose windows need washing and whosefence needs repairing.
