美國副總統(tǒng)官邸準備加強安全裝置。 "The Vice President's official residence is getting a $1.7 million security upgrade," 副總統(tǒng)官邸要進行耗資170萬美元的保安系統(tǒng)升級。市場調(diào)查顯示, "Many customers are putting off plans to upgrade their cell phones during the economic downturn," 經(jīng)濟不景氣,使很多顧客推遲手機升級的計劃。好的,今天我們學習的詞upgrade...