题目

（08年福州质检理）从依次标着数字0，1，2，3的六张号码牌中不放回地随机选取两张，这两张号码牌的数字之和的数学期望E=            .p{font-size:10.5pt;line-height:150%;margin:0;padding:0;}td{font-size:10.5pt;} 答案：答案：3  p{font-size:10.5pt;text-align:left;line-height:150%;margin:0;padding:0;}td{font-size:10.5pt;text-align:left;}—______, madam? ( )—Yes, please. I want to buy some books.A.What do you doB.How do you doC.Can I help you