题目

Sydney —— A shark savaged a schoolboy’s leg while he was surfing with his father at a beach in Sydney on February 23. It was the third shark attack along the coast of Australia’s largest city in a month. The 15-year-old boy and his father were in the water off Avalon, on Sydney’s northern beaches, around dawn when he was attacked. The city’s beaches are packed with locals and tourists during the summer months. “The father heard a scream and turned to see his son thrashing(激烈扭动)about in the water,” the police said. “Fortunately, the shark swam away and the boy 已知点P是△ABC的中位线EF上任意一点，且EF∥BC．设△ABC，△PBC，△PCA，△PAB的面积分别为S，S1，S2，S3，记，，，定义M（P）=（λ1，λ2，λ3）．当λ2•λ3取最大值时，则M（P）等于（ ）A．B．C．D．