Pumas never attack a human being except when the are cornered

题目

Pumas never attack a human being except when the are cornered
帮我分析下句子成分,还有when这里引导的是状语从句吗?
when 引导的如果是状语从句,那么属于哪种呢?感觉不会是时间状语吧?

答案

Pumas never attack a human being except when they are cornered
美洲狮从来不会主动攻击人类除非他们被逼无奈.
when是引导状语从句
a human being指人
主句就是：Pumas never attack a human being.