这条双向公路连接了两个城市。

The ___two-way highway connects two cities.

良好的师生关系建立在双向交流的基础上。

A good teacher-student relationship is built on ___two-way communication.

这扇门是双向的，可以从里外两边打开。

This door is ___two-way, it can be opened from both inside and outside.