postbox

I dropped my letter into the postbox on the corner before heading to work.

用法提示：这里的 postbox 是名词，指街头的公共邮箱，可用于投放信件。

There is a postbox outside the library, so you can mail the card on your way.

用法提示：postbox 是可数名词，表示公共邮箱，句子用它指代邮筒这个地点。

She walked to the postbox at the end of the street to send her application.

用法提示：postbox 在本句中作宾语，指用于收寄邮件的公共邮箱。