【正确答案】 B

【答案解析】[解析] 本题考查的是对形容词的认知能力。本句意思：许多人喝脏水后都会生病。A．boiled：煮沸的，例如：The milk had boiled over．牛奶已沸腾得溢出来。B．polluted：被污染的．与contaminated：被污染的、弄脏的意思相近；C．mixed：混合的，弄糊涂的，例如：He had some mixed pickles and rice for supper．他晚饭吃了一些什锦泡菜和米饭。D．sweetened：变甜的，例如：A usually sweetened bread is baked first as a loaf and later cut into slices and toasted．烤干面包通常先将甜面包烘制成块，然后切成片烤。