济南八中的初三毕业生李宗龙拿到自己的中考成绩后，就迫不及待想和同学去将来的高中看看，没想到自己一不小心把停放在路边的一辆车的后视镜撞坏了。他当时很紧张，也很害怕，意识到闯祸了。但是他觉得不能跑，他想等车主来，但等了一段时间，不见有人来，他就和同学从附近的一家快餐店借了一张纸和一支笔，留下了一张字条，纸条上写着：“尊敬的车主，对不起，我撞坏了你的后视镜。如欲索赔，请拨150××××4521找我，我对此深表歉意。一个不愿犯错误的人。”他把纸条夹到车的雨刷下才离开。

根据短文内容，选择最佳答案。

    Are you able to send a letter with pictures and sounds to someone somewhere in the world without a stamp(邮票) on it? Using a computer you can send e-mails quickly and easily. The post is much slower than e-mail. E-mail can send its message to the other side of the world in seconds.

    E-mail is easy to use and it saves time and money. The differences in time in different parts of the world do not matter when sending e-mail. It's twenty-four-hour service(服务) that you can send e-mail at any time of the day or night. No one has to be there to get e-mail. It does not matter if your friends are in beds when you send e-mail to them, or you are seeing a movie at the movie theater when they send e-mail back.

法国大革命高举反封建专制的旗帜，震撼了整个欧洲大陆的封建秩序。如图所示人物把法国大革命推向高潮的是（　　）

有理数a、b在数轴上的位置如图所示，那么下列式子中成立的是（   ）

当a=3，b=﹣1时，代数式 $a^2-\frac{a}{b}$ 的值是____．