题目

_________ in the leg made it impossible for him to walk home.    A. Injured     B. Having injured     C. To be injured      D. Being injured 答案：D已知变量x、y满足条件设z＝2x＋y，取点(3，2)可求得z＝8，取点(5，2)可求得，取点(1，1)可求得，取点(0，0)可求得z＝0，则点(3，2)叫做_____，点(0，0)叫做____．点(5，2)和点(1，1)均叫做_____．