用所给单词的适当形式填空。
1. The pen isn't mine, but I can't find the_          (own).
2. I can't see the words _       _ (clear)  on the blackboard.
3. Beethoven was one of the most famous             (music) in the world.
4. The boys make much _       _ (noise) sound as usual.
5. The famous _       _ (history) gave us a report about Chinese History.