题目

    When women sit together to watch a movie on TV, they usually talk simultaneously(同时地) about a variety of subjects, including children, men, careers and what’s happening in their lives. When groups of men and women watch a movie together, the men usually end up telling the women to shut up. Men can either talk or watch the screen—they can’t do both—and they don’t understand that women can. Besides, women consider that the point of all getting together is to have a good time and develop relationships—not just to sit there like couch potatoes staring at the screen.设a，b∈R，a2+b2=2，则a+b的最大值是    ．