tract

呼吸系统包括鼻腔和肺。

The respiratory ___tract includes the nose and lungs.

呼吸道感染会影响整个呼吸系统。

Respiratory infections can affect the entire ___tract.

她写了一本关于和平的小册子分发给社区居民。

She wrote a ___tract on peace and handed it out to the neighborhood.