我国从免除学杂费、免费提供教科书，到免除农村寄宿生住宿费，不断改善农村中小学生学习生活条件，这主要是为了（     ）

看图回答问题：

①哪些物体的形状是长方体？____

②哪些物体的形状是圆柱体？____

③哪些物体的形状是球体？____

④哪些物体的形状是正方体？____

如图是氯元素、钠元素在周期表中的位置及相关的结构示意图，据图回答下列问题：

氯元素的原子序数为____ 　；钠元素的相对原子质量为　____ 　；属于氯原子的结构示意图是____ （填序号）；氯原子的电子层数为____ 　层；钠元素与氯元素形成化合物的化学式为　____ ．

根据短文理解选择最佳答案。

    Michael Jordan is the most famous basketball player in the world. He was born in Brooklyn, New York. He didn't like to talk to other people about himself. He was also very short. He didn't play very well when he joined the basketball team in his high school at first. But the next year things changed greatly for him as he grew much taller.

    Michael Jordan became famous when he joined the university basketball team in North Carolina. Michael used his speed and strength (力量) to reach the basket again. He played so well that people called him “Air Jordan”.

    After college, Michael became a basketball team member in the Chicago Bulls. The NBA was very surprised at this high-flying player. He was named “Rookie” (新秀) of the year in 1985 and “Most Valuable (价值的) Player” in 1987. He once set a record (创纪录) by getting 63 points in one game.