1、And it gets worse. By 2020, first-class mail volume is expected to drop by half.
2020年的情況會更糟，一類郵件數(shù)量預(yù)計(jì)將減少一半。

2、It arrived by first-class mail in second-class condition.
那是第一級的郵件，收到時卻處于第二級狀態(tài)。

3、And it gets worse.By 2020, first-class mail volume is expected to drop by half.
2020年的情況會更糟，一類郵件數(shù)量預(yù)計(jì)將減少一半。