短语讲解：
1. This, as the United Nations faces a lawsuit for alleged unsanitary conditions at a U.N. base that may have introduced cholera into Haiti.
introduce into引进; 插入
例句：Tea was introduced into Europe from Asia.
茶叶是从亚洲传入欧洲的。
2. Susan" won't give her real name because of the stigma of her disease.
because of因为, 由于
例句：I came back because of the rain.
因为下雨, 所以我回来了。
3. She walked and rode motorcycles for six hours to arrive at this cholera treatment center.
arrive at到达, 来到
例句：One day a letter from my father arrived at the school.
有一天, 学校收到了我父亲的一封信。
4. And a U.N. panel of experts has traced it back to Nepalese peacekeepers at this U.N. base.
trace back to追溯到…
例句：The rumor has been traced back to a bad man.
那谣言经追查是个坏人造的。
5. So, meantime, the centers train Haitians to treat drinking water with chlorine tablets and to practice good hygiene.
treat with用防护措施处理某物
例句：New timber should be treated with a preservative.
新采的圆木应进行防腐处理。
