题目

阅读理解；阅读下列内容，从每小题所给的A、B、C、D四个选项中选出一个最佳答案 Invitation(邀请) to a going-away party Wednesday, 17 May Dear Lucy and Jack, You are invited to a farewell(告别) for the “White family’s visit to Africa”.    Departure(离开) Date: 6 July     The best part of their big adventure(冒险) to Africa will be when they come face-to-face with lions, elephants and other African wildlife. They have always wanted to do this. Party given by: Mr. and Mrs. White, Eric and Tom Date: Saturday, 8 June.            在区间[0，1]上任取两个数a，b，方程x2+ax+b2=0的两根均为实数的概率为（　　）A．18B．14C．12D．34