题目

---Mary, I’m getting fatter and fatter!---No worry about not __________weight in a month. The Baodi Fit Club will promise you_________, or you can get your money back.A．lose; success B．losing; success C．to lose; successfulD．losing; successfully 答案：B解析:略已知A、B是圆O：x2+y2=16上的两点，且|AB|=6，若以AB为直径的圆M恰好经过点C（1，-1），则圆心M的轨迹方程是    ．