22．People in the United States in the nineteenth century were hauntedby the prospect that unprecedented change in the nation's economy would bringsocial chaos．

(同位语从句prospect that…)

19世纪的美国人因为害怕国家经济中史无前例的变化会带来社会混乱这一前景而提心吊胆。

分句1： People in the United States in the nineteenth century were haunted by theprospect

分句2： unprecedented change in the nation's economy would bring social chaos．

1和2 嵌套，

1是主句，2 具体解释说明prospect