Why didn’t my teacher believe(相信) me? I’m a good student. I

Why didn’t my teacher believe(相信) me? I’m a good student. I really did all my homework last night, though I don’t have it now.
My teacher knows I’m busy these days. 小题1: I’m on the basketball team and have to practice after school every day. 小题2:
Where is my homework? I have to say, my dog ate it.
Here is the story: Last night, I went home late and was really tired after practice. However, I didn’t forget to do my homework. I ate dinner and did it at the time. When I finished it, I suddenly dropped some meat on my paper. 小题3: What should I do? It was too late, I couldn’t do the homework again on another piece of paper. 小题4: Later, my dog Max, who loves meat very much, jumped up onto the table and ate my homework!
My teacher said it was an old story. 小题5: It is true this time, but no one believes me.