这台打印机的内部结构非常精密，各个部件协同工作。

The ___mechanisms inside this printer work together precisely.

研究人员正在探索免疫系统抵抗病毒的具体机制。

Researchers are investigating the ___mechanisms by which the immune system fights viruses.

学校引入了新的机制来鼓励学生参与课外活动。

The school introduced new ___mechanisms to encourage student participation in extracurricular activities.