‘ adults in the United States who have not yet received ……

'adults in the United States who have not yet received a COVID-19 vaccine'

这限制性定语，讲了三要素：成人；在美国；以前没有接种过疫苗。

 

完蛋了，总统（白等）了。俺去年初打了两P，还指望着用这玩艺当B呢。