已知一个空瓶子装满水后的总质量为300g，在装满水的瓶子中放入一个小石块，溢出水后其总成量为320g，取出石块后，剩余的水和瓶子的总质量为290g．（不计取出石块的过程中带走的水）则石块的质量为多少？石块的密度为多大？（ρ_水=1.0×10³kg/m³）

根据短文内容，选择最佳答案。

    I love listening to music and will try to do it as much as I can. Whether I'm driving my car or walking somewhere I always have a CD or my iPod playing because I feel music can greatly influence my mood (情绪). I can listen to music to cheer me up or relax me or remind me about a certain time and a certain place where I last listened to that song.

    I feel the best way to listen to music is live! I love going to concerts to watch and hear my favorite artist or band perform. The last concert I went to was a Mumford and Son's concert in Newcastle, a country-folk style band from the UK. All of the lights and sound effects not only sounded good but also looked good.

    I always feel that people come together at concerts. I can easily talk to people I might never have talked to before, just because they share an interest in a certain music artist.

    I also find that at concerts many artists or bands may speed their song up or slow it down. Sometimes they might cover someone else's song so I feel that the live performances really show me a new way to listen to music.

    I enjoy concerts because I always discover something new and different because of the way it is played live.

如图，天花板上相距120cm的A、B两点分别悬挂着两根轻质弹簧，两弹簧的另一端在O点相连．现在O点悬挂一质量为m=5kg的重物，待稳定后量得两弹簧长度均为65cm；将重物换为质量为M=16kg的另一重物，稳定后经测量知弹簧OA与弹簧OB垂直，且弹簧OA与水平面夹角为53°（sin53°=0.8）．试求两根弹簧的劲度系数．（g=10N/kg）

         orange key ring is Timmy's. It's        present from Neil.

下列句子组成语段，顺序排列最恰当的一项是（    ）

①教育家苏霍姆林斯基曾说：“一所学校可以什么都没有，只要有了为教师和学生精神成长而提供的图书，那就是学校了。”

②应该认识到，阅读是学校教育的重要组成部分，一个孩子如果在十多年的教育历程中没有养成阅读的习惯、兴趣和能力，一旦离幵校园，很可能把书永远丢弃在一边，这样的结果一定是我们所有的教育工作者不想看到的。

③对教育来说，阅读是最基础的教学手段，教育里最关键、最重要的基石就是阅读。

④但是现在，我们的教育在一定程度上，还不够重视阅读，尤其是延伸阅读和课外阅读。