alert|alerted

一只年轻的狗应该机警而活泼。

A young dog should be ___alert and playful.

这项新研究警告政策制定者迫切需要采取气候行动。

The new study ___alerted policymakers to the urgent need for climate action.

教师需要对学生行为的突然变化保持警觉。

Teachers need to be ___alert to sudden changes in students' behavior.