今天我们要学的词是upgrade。 Upgrade, 升级。 "The local elementary school received a library upgrade thanks to donations from the alumni association," 校友会的慷慨捐赠，让本地小学图书馆焕然一新。

美国副总统官邸准备加强安全装置。 "The Vice President's official residence is getting a $1.7 million security upgrade," 副总统官邸要进行耗资170万美元的保安系统升级。市场调查显示， "Many customers are putting off plans to upgrade their cell phones during the economic downturn," 经济不景气，使很多顾客推迟手机升级的计划。好的，今天我们学习的词upgrade...