关于一个英文现在分词的用法his form evolving from an earlier cartoon character called Brother Jonathan为什么不是is evolving from呢?

问题描述:

关于一个英文现在分词的用法
his form evolving from an earlier cartoon character called Brother Jonathan为什么不是is evolving from呢?

这句话的主语是his form called called Brother Jonathan,而evolving from an earlier cartoon character 是做his form的 相当于后置定语,不可以加is,加以后句子就会出现两个谓语,那是不符合语法的