老师们经常表扬他在课堂上礼貌的行为。

Teachers often praise his polite ___behaviours in class.

研究人员观察了鸟类在不同季节的迁徙行为。

Researchers observed the migratory ___behaviours of birds across different seasons.

这台机器的不稳定行为导致了生产线停工。

The unstable ___behaviours of this machine caused the production line to stop.