根据句意及首字母的提示，补全单词。

1. Taiwan b           to China forever.

2. Jack is still standing outside b        _ of his being late.

3. My math teacher is one of my r_        .  He is my uncle.

4. The Great Wall is well k_         in the world.

5. You must pay attention to the e        _ when you are on duty on the mountain.