VOA慢速英语:词汇节目:千载难逢

lunar – adj. of or relating to the moon

phenomenon – n. something (such as an interesting fact or event) that can be observed and studied and that typically is unusual or difficult to understand or explain fully

infrequent – adj. not happening often : not frequent

rare – adj. very uncommon

seldom – adj. not often : almost never

eternity – n. time that seems to be without an end