underwrite (v.) underworld (n.) underwhelm (v.) underweight (adj.) underwear (n.) underway (adv.) underwater (adj.) undervalue (v.) underutilize (v.) undertow (n.) undertone (n.) undertaking (n.) undertakes v.承担；从事；保证；答应undertaker (n.) undertake (v.) understudy (v.) understory (n.) understatement (n.) understated (adj.) understate (v.)