题目

Today's teens have a knowledge of the Internet that often surpasses that of their parents. Because so many teens are Internet survey, it is important that they also have an understanding of the dangers that exist online and how to deal with them. Watch teens share their own“Real­Life Stories” about issues affecting them on the Internet such as cyberbullying(网络欺凌), online enticement, and giving out too much personal information. NSTeens—Terrible Text Some teens say and do terrible things to each other online because they don't see the direct effects of their actions. So w（　　）是轴对称图形． A、梯形B、等腰三角形C、四边形