In data communications, the transmission by a receiver of acknowledge characters as an affirmative response to a sender.
数据通信中，由接收方向发送方传送应答字符作为肯定回答的传输过程。
A batch of mail dispatched at one time by a sender.
由邮递员同时分送的一批邮件
The parcel was returned to the sender because the directions were incorrect.
包裹因姓名地址有误而退给了寄件人.
