Mobile phones are becoming more and more popular not only with____(grown-up) but also with students. Meanwhile,they also____(become) a problem for middle schools in the past few years.Some children have got mobile phones____Christmas or birthday gifts,and more will still want them.

    Many like SMS because it is____(ease) and quick.Some parents felt happy because they could communicate with their children.Some teachers said mobile phone use____(be) a distraction（分心的事）to students during school hours and____also gave them much trouble in their classrooms.Sometimes students might use phone messages____(cheat) during exams.A new study found that some teenagers sending messages in class even hurt their fingers because they can't stop____(send) SMS.

    Many teachers suggested that students should not have phones at school,but if there was a good reason,they could leave their phones at school office.And even they can use the telephone in the teachers' office instead.Many people think they understand the reason____parents would want their children to have them,but they agree schools should tell the students____(use) their mobile phones at proper times.

海上有风时，海面出现波浪，某区域海面呈圆弧形，O为圆心，圆弧形海面正下方的水中有一条鱼（用箭头AB表示），如图所示．此时，从圆弧形海面上方看到了水中的这条“鱼”．看到的“鱼”是鱼的缩小的虚像，请分析说明其原因．（注：可以在图上画光路图，以辅助说明）