ugly /adj. 難看的：Where did you get that ugly dog? 你從哪裏弄到那隻難看的狗？/The city is full of ugly buildings. 這個城市充滿難看的建築。
UK /（=United Kingdom） n. 英國
umbrella［E］/n. ［U］傘：Put your umbrella up. It's going to rain. 把你的傘撐起來。天要下雨了。/A strong wind came from behind suddenly and blew our umbrellas away. 一陣強風從後麵突然吹來，刮走了我們的傘。
uncle［E］/n. ［C］叔父；伯父；舅父；姑父；姨父
under［E］/prep. 在…下麵；以下；在…之中：I found my pen under the table. 我在桌子下麵找到了我的筆。/He can stay under water for a long time. 他可以在水下麵待很長時間。/These books are written for children under 12. 這些書是為12歲以下兒童寫的。/This matter is still under discussion. 這件事仍在討論之中。/A fire was started and soon kept under control. 起火了，但火很快被控製住了。
underground /adj. 地下的；-n. ［C］地鐵：There is an underground car park in the center of the city. 在市中心有一個地下停車場。/The best way is to take the underground and it takes only 20 minutes to get there. 最好的辦法是乘地鐵，到那裏隻需要20分鍾。
understand /v. （understood /，understood/）懂；理解；了解：He doesn't understand Chinese. 他不懂中文。/We should help people understand the importance of protecting environment. 我們應該幫助人們理解保護環境的重要性。/If you cannot do it，I can understand. 如果你不能做此事，我能理解。/We do not understand how our brain works. 我們不了解我們的大腦如何運作。
unit /n. ［C］單位；單元：The family is the smallest social unit. 家庭是最小的社會單位。/How many units are there in this textbook? 這本教材有多少單元？
university /n. ［C］大學：He is a student in a medical university. 他是一所醫科大學的學生。/He wants to enter a good university. 他想上一所好大學。
unless /conj. 如果不；除非…否則；除非：He won't come unless he is invited. 如果不被邀請，他是不會來的。/A tourist will easily lose his way in Beijing unless he has a map or a guide. 除非有地圖或導遊，否則遊客很容易在北京迷路。/He can not watch TV unless he finishes his homework. 他不能看電視，除非完成作業。