（1）在水溶液中，YO₃^n﹣和S^2﹣发生反应的离子方程式如下：YO₃^n﹣+3S^2﹣+6H⁺═Y^﹣+3S↓+3H₂O，已知Y为1～18号元素．

（a）YO₃^n﹣中Y的化合价是 ____　； Y元素原子的最外层电子数是　 ____　；

（b） S^2﹣的半径 ____Y^﹣的半径（填“大于”或“小于”）．

（2）在一定条件下A与B反应可生成C和D，其能量变化如图

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（a）若E₁＞E₂，反应体系的总能量 ____（填“升高”“降低”），为 ____ （填“吸  热”“放热”）

（b）若E₁＜E₂，反应体系的总能量 ____（填“升高”“降低”），为 ____ （填“吸热”“放热”）反应．

阅读下列文字并思考：

普通的家用煤炉燃烧无烟煤，燃烧效率只有15％；普通燃煤锅炉，燃烧效率约为30％；现代化的锅炉，燃烧效率可达90％左右。

句子修辞我知道。

先通读下面的短文，掌握其大意，然后从A、B、C、D四个选项中选择可以填入空白处的最佳答案。

    Do you like music?Do you know about Beethoven,a famous1in the world?

    He was born in Germany．His father was a singer and2Beethoven．When Beethoven was only four,his3asked him to learn different musical instruments(乐器).Beethoven loved music and he4very fast.He got high praise(赞扬）from Mozart ,the great musician at that time,5the age of seventeen.

    At that time ,it was difficult to have6happy life.Beethoven was hard-working，but it wasn't easy to make much money．One day,he found he couldn't7clearly．But he still went on working and writing music pieces．Some of his best pieces came out8he lost his heating．In 1827，9more than 300 pieces，the great musician died．But people remember his name and10today．