China was attacking France, everyone started screaming, and the look of panic on my history teacher's face was almost funny.

look 在这里是名词用法，意思是"表情、神色"，特指面部呈现出的某种情绪状态。这个词由动词"看"的本义引申而来，表示通过面部表情"显露"出的状态。 panic 指"恐慌、惊慌"，源自希腊神话中潘神(Pan)的名字，传说潘神会突然出现引发人群的极度恐惧。在句中作名词修饰look，表示"恐慌的表情"。