单选题 Huntington and many of its competitors are working to make remedial instruction a commodity as ______ and accessible as frozen yogurt.

A、 ubiquitous
B、 rational
C、 necessary
D、 credible

【正确答案】 A

【答案解析】[解析] 本句空格处指的是像冻酸奶一样普遍。ubiquitous意为“普遍存在的”，如： The struggle between opposites is ubiquitous．(对立面的斗争无所不在。)其他三项“rational理智的；necessary必要的；credible可以相信的”都与句意不符。