gǔ dài / jūn duì / cháng yòng / xiǎng jiàn / chuán dì / xìn hào / dí wǒ / shuāng fāng / dōu / néng / tīng dào

古代军队常用响箭传递信号，敌我双方都能听到。

Ancient armies often used whistling arrows to transmit signals, which both sides could hear.