The gift of being able to describe a face accurately is a rare one. As a professor 【B1】 it recently: "When we try to describe faces precisely words 【B2】 us, and we 【B3】 to identikit (拼脸型图) procedures." 【B4】 . according to a research 【B5】 this subject, we can each probably recognize more than 1,000 faces, the majority of which differ in 【B6】 details. This, when one comes to think of it, is a 【B7】 feat, though, curiously enough, relatively little attention has been devoted to the fundamental problems of how and why we 【B8】 this gift for recognizing and remembering faces. Some scientists argue that it is an inborn 【B9】 . and that there are "special characteristics about the brain’’s 【B10】 to distinguish faces". On the other hand, there are those, and they are probably 【B11】 the majority, who claim that the gift is an acquired one. But 【B12】 all these arguments, sight is predominant. 【B13】 at the very beginning of life, the ability to recognize faces quickly becomes an 【B14】 habit, one that is essential for daily living, if not 【B15】 for survival. How essential and valuable it is we probably do not 【B16】 until we encounter people who have been 【B17】 of the faculty (能力). This unfortunate inability to recognize familiar faces is known to all, 【B18】 such people can often recognize individuals by their voices or their walking manners. With typical human 【B19】 many of these unfortunate people overcome their handicap by recognizing other 【B20】 features.

A．but
B．therefore
C．in addition
D．so