1.social media 社交网络
例句:We have all witnessed the power of social media.
我们见证了社交媒体的实力。
2.back down 放弃；让步
例句:He had to back down on plans to backdate the tax changes.
他不得不放弃追溯税收调整的计划。
3.ruled out 排除
例句:The possibility of suicide was ruled out.
自杀的可能性已被排除。
4.tax rate 税率
例句:For low-paid workers, the marginal tax rate is at least 75%.
对于低收入的工人来说，边际税率至少为75%。
