用所给词的适当形式填空。

1. I enjoy _             (swim) in the river.    

2. The best way of learning English is by               (use) it.      

3. A good language                (learn) should have lots of practice.      

4. When I hear the _            (exciting) news, we all got _             (excite).      

5. His father was very _             (frustrating) because he was always for school.