参考答案

正确答案：C
解析：细节题。本题问的是：对于绝大多数能阅读的青少年来说，最大的问题是______。根据第2段第2句和第4句“It has been suggested that almost 80 percent of America's literate， educated teenagers can no longer read without an accompanying noise(music in the background or a television screen flickering(闪烁)at the corner of their field of perception．”“this new form. of partreading，of part-perception against background distraction，renders impossible certain essential acts of apprehension and concentration”可知80%的有阅读能力的受教育的青少年在无背景噪音(音乐)或在他们视野之内的闪烁银屏的陪伴下无法阅读。而且这种在有背景干扰下的半知半解，是不可能达到理解和专注的。因此他们的最大问题是理解和专注，故选C 。