在城市里，自行车是一种环保的交通方式。

A bicycle is an eco-friendly ___mode of transport in the city.

在线课程和面授课程是两种常见的教育模式。

Online and in-person classes are two common ___modes of education.

在会议期间，将设备调至静音模式是处理通知最礼貌的方式。

Switching to a silent ___mode is the most polite way to handle notifications during a meeting.