根据句意及首字母或汉语提示完成单词。

1. I won't believe it until I see it with my o______ eyes.

2. My parents tell me not to c______ other's homework. It's bad for study.

3. Tom was really  l______ to get the singer star's autograph.

4. My best friend Lu Ming is always ______ (紧张的) before a big exam. That's why he can't get good grades.

5. Could you please buy me an ______ (信封) when you go to the post office?