单选题 Chinatown has been the center of San Francisco's Chinese community since the 1850s. Its boundaries have expanded significantly since the 1960s, and the neighborhoods built there are generally {{U}}wealthy{{/U}}.
【正确答案】 D
【答案解析】该句意为：自19世纪50年代起唐人街就已成为旧金山华人社区的中心。20世纪60年代以来其范围扩大很多，而这时在此建立的居民社区一般都比较富裕。wealthy：有钱的，富裕的；plentiful：大量的；attractive：吸引人的；friendly：较好的。