题目

Five years ago, David Smith wore an expensive suit to work every day. “I was a clothes addict(迷),” he jokes. “I used to carry a fresh suit to work with me so I could change if my clothes got wrinkled(皱的).” Today David wears casual clothes — khaki pants and a sports shirt — to the office. He hardly ever wears a necktie. “I’m working harder than ever,” David says, “and I need to feel comfortable.” More and more companies are allowing their office workers to wear casual clothes to work. In the United States, the changes from formal to casual office wear have been如图，直线与轴，轴分别相交于A，B两点，C为OB上一点，且∠1=∠2，则S△ABC="…………………………("      )A．1B．2 C．3D．4