315. undermine v. 暗中破坏
316. undergo v. 经历 ~ great changes
317. underlying a. 潜在的
318. uphold v. 支持 ~ world peace
319. vent n.. 排放口 give ~ to(发泄)
320. verge n. 边缘 =brink> on the verge of bankruptcy
321. versatile a. 多才多艺的
322. vicinity n. 附近 in the ~
323. visa n. 签证
324. visualize v. 设想