题目

—It's time for lunch, Mum! I am hungry.—_________ A . I'm sorry to hear that. B . OK. Let's make some sandwiches. C . That's all right. D . Never mind. 答案：B如果方程组x+y=3mx+ny=8与方程组x-y=1mx-ny=4有相同解，则n=22，m=33．