题目

       ________ a person does is not always the same as ________ he says. A．what; what    B．what; that     C．that; that     D．that; what 答案：A关于x、y的方程组ax+y=1x+by=-3的解为x=-1y=2，则a+b的值是（　　） A、-2B、-1C、0D、1