What's a letter box?It's a box with a hole through which the postman puts the letters.我大概知道这题是要做什么 可是为什么是这样做呢?

问题描述:

What's a letter box?It's a box with a hole through which the postman puts the letters.
我大概知道这题是要做什么 可是为什么是这样做呢?