这个实验是化学反应的一个很好例子。

This experiment is a good ___example of a chemical reaction.

老师通过耐心对待每个学生树立了良好榜样。

The teacher set a great ___example by being patient with every student.

老师严厉惩罚了那个捣蛋的学生，以儆效尤。

The teacher made an ___example of the troublemaker by giving him a strict punishment.