@saugarmaripuri It says that the USPS tests come from a stockpile that was purchased long ago for the purpose of having them on hand, something retailers don't usually do. In terms of effectiveness, they're supposedly fine much longer (I have no reason to doubt this).
@saugarmaripuri 它说 USPS 测试来自很久以前购买的库存，目的是让它们在手边，零售商通常不会这样做。就有效性而言，它们应该可以使用更长的时间（我没有理由怀疑这一点）。