雙向通行
最貼近核心畫面的一家：真的有東西在兩個方向上移動。
adjective · B1
Moving in both directions, or built so that people, vehicles or goods can move in both directions.
雙向的
核心畫面
Picture a road that is open at both ends. Something can travel toward you and away from you along the same line, at the same time. Once you hold that picture, the other uses fall into place: the thing travelling can be cars, it can be goods, it can be words on a radio, it can be effort between two people, or it can be a player working at both ends of a court.
可以想成一條兩頭都通的路。東西可以朝你過來，也可以離你而去，走的是同一條線。抓住這個畫面，其他用法就會自己就位：在路…更多收起
可以想成一條兩頭都通的路。東西可以朝你過來，也可以離你而去，走的是同一條線。抓住這個畫面，其他用法就會自己就位：在路上跑的可能是車，可能是貨，可能是無線電裡的聲音，可能是兩個人之間的付出，也可能是球場上那個兩端都要顧的球員。每次看到 two-way，先問一句：是哪兩個方向。From the word’s history
Wiktionary derives it from two + way, and compares Old English twiweġ, 'an intersection, a junction of two roads'. The road picture is therefore already in the parts of the word.
維基詞典說 two-way 來自 two 加 way，並拿古英文的 twiweġ 作比較，那個字指「兩條路交會的地方」。也就是說，「路」的畫面本來就藏在這個字的組成裡，今天的各種用法都還看得到它。
Wiktionary 'two-way'（封包 source_ref kaikki:3f6f69a190036ae4:1148693094）
Four branches
雙方互相
把路上跑的東西換成人的付出：兩邊都得走，這條關係才通得了。
adjective · B2
Used about a relationship or process in which both sides have to give something and do their part.
雙方互相的
收發兩端
這次在路上跑的是聲音和訊息：出得去，也回得來。
adjective · B2
Used about a radio or a similar device that can both send and receive messages, so two people can talk to each other.
可收發雙向通訊的
攻守兩頭
兩個方向變成球場的兩端：一端進攻，一端防守，兩頭都要跑。
adjective · C1
Used about a player who plays well at both ends of the game, in attack and in defence.
攻守兼備的