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.