vicious

The explorer warned us that the vicious predators in this jungle hunt primarily at night.

(Chinese) 探险家警告我们，这片丛林中凶猛的捕食者主要在夜间狩猎。

The vicious cycle of poverty and lack of education is difficult to break without outside help.

(Chinese) 如果没有外部帮助，贫困与缺乏教育的恶性循环很难打破。