2--I might be able to help you.

1--Really? That would be great!

2--What's your classroom number?

1--My classroom number is A21.

2--So the "A" is the building type.

1--Okay, but I don't know where that is.

2--Do you know where the gym is?

1--Yeah, I do.

2--Okay, your classroom is behind the gym.

1--That's really helpful! Thank you.

2--No problem, and the "21" means it's upstairs.

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注解：

1.classroom教室
2.building type建筑类型  
3.upstairs楼层 

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译文：

1--我花了几个小时才找到教室。

2--我或许能帮到你。

1--真的吗？那真好！

2--你的教室号是多少？

1--我的教室是A21.

2--所以A是楼号。

1--嗯，但我不知道它在哪。

2--你知道体育馆在哪吗？

1--是的，我知道。

2--好的，你的教室就在体育馆后面。

1--你真的帮到我了！谢谢你。

2--没问题，21代表楼层。