U11. underline-U12. undermine-U13. undoubtedly

underline

构词：under-（在...下面）＋line（划线）

在…下面画线 v. 突出强调。

相关：linage, airline, byline, deadline, hairline, online, outline

搭配：underline the page / words / fact / importance / concern / risk

近义：emphasize, stress, highlight

考点：同义替换

undermine

构词：under-（在...下面）＋mine（挖矿）

“挖墙脚” v. 在…下面挖, 逐渐削弱, 故意破坏。

相关：goldmine, minefield; miner, mining, mineral

搭配：undermine one’s position / effort / confidence / credibility 

近义：disable, weaken, damage, injure, hurt, impair, sabotage

考点：负面消极方向

undoubtedly

构词：un（否定）＋doubt（怀疑）＋-ed（adj.）＋-ly（adv.）

无疑 adv. 肯定

相关：two, double, duplicate, dubious; doubtful, doubtless

搭配：Undoubtedly, it is undoubtedly the best..., will undoubtedly rise / decline

近义：without/ beyond doubt, doubtless, certainly, definitely, surely