get可用作系动词,系动词后可直接接形容词,这就是这里的用法..
类似的还有:
The flower is turning red,花儿变红了.
She got anxious.她变得焦虑了.
英语中常用的系动词有：
be(am,is,are/was,were)
look,seem,appear
feel,sound,smell,taste
go,get,turn,become,grow,run
rest,promise,fall
keep,remain,hold,continue
lie,sit,stand
prove(to be)=turn out (to be)