cock an ear at 侧耳倾听；凝神细看

【例句】
He suddenly cocked an ear at his mother.
他突然侧耳倾听他妈妈的话。

You need to cock an ear at your teacher when you're in class so thatyou know what your homework assignments are.
你上课的时候要认真听老师的话，这样你才能知道你的作业是什么。