题目

Large quantities of money _________ spent on the project so far; it is enough. A . is B . were C . has been D . have been 答案：D将正整数1，2，3，4，5，6，7随机分成两组，使得每组至少有一个数，则两组中各数之和相等的概率是（　　）A．221B．463C．121D．263