题目

Mobile phone has become a problem for middle schools. Some middle schools in Australia have banned students from carrying mobile phones during school hours. Mobile phone use among children has become a problem for the school this year. Several children have got mobile phones as Christmas gifts, and more students will want them.Mary Bluett, an official, said mobile phone’s use is a distraction to students during school hours and it also gives teachers so much trouble in their classrooms. Teachers were also saying that sometimes students might use phone messages to cheat during exams.She said 已知x2+2xy=3，y2=2，则代数式2x2+4xy+y2的值为A.8B.9C.11D.12