To cling onto something means to hold tightly, either with your hands like clinging onto to a rope or with your mind like clinging onto an idea or your heritage.

• 就是抓住什么东西不放的意思,比如用手抓住绳子,或者说对一个想法不愿意放弃。说到继承文化遗产,对于美国这个多民族的国家,维护各民族的文化有什么重要意义呢?