钥匙

例句：

1. 1.She found the key to the door and opened it.
   她找到了钥匙，打开了门。
2. 2.The key to solving this problem is to think creatively.
   解决这个问题的关键是要有创造性地思考。
3. 3. He used the key to unlock the safe.
   他用钥匙打开了保险箱。