求问一道题目？

长白山的大丈夫

The themes that Rita Dove explores in her poetry is universal, encompassing much of the human condition while occasionally she deals with racial issues.
划线部分为红色
正确答案是:are universal, they encompass much of the human condition and occasionally deals
前面因为主语是themes所以is 改成are能理解，后面为什么要改成and?逗号后半句算是完整的句子吗？

marjoriee

你确定这是正确答案吗？？
因为是SVO,SVO的run-on句型

后半句改为and是因为 the human condition 和 deals with racial issues不是转折的关系，说
的都是人类的事儿，所以用and并列吧。。