lt's a hard and small thing.you can use it to open the door or the box.这是什么.

lt's a hard and small thing.you can use it to open the door or the box.这是什么.
lt's a hard and small thing.you can use it to open the door or the box.
这是什么.

lt's a hard and small thing.you can use it to open the door or the box.这是什么.
key钥匙

a key