题目

People think of cats as cute. But research published in a psychology journal calls them neurotic and unstable. Researchers from the University of Edinburgh in Scotland and the Bronx Zoo in New York compared the personalities of domestic house cats with those of four different types of wildcats.To better understand their personalities, the researchers rated a number of animals’ behaviors on what psychologists call the Big Five human personality traits: openness, agreeableness, conscientiousness, neuroticism and extraversion.Domestic house cats have similar personality structures to African li某几何体的一条棱长为，在该几何体的正视图中，这条棱的投影是长为的线段，在该几何体的侧视图与俯视图中，这条棱的投影分别是长为a和b的线段，则a + b的最大值为（    ） A. B. C.           D. 4