根据短文内容，选择正确答案。

     Dabing and Xiaowei usually go to school by car. They drive past a cinema, a supermarket and a toy shop. The toy shop is next to the supermarket. Yaya and Xiaoli usually go to school by bus. They go past a bank and a post office. The bank is next to the post office. Longlong usually goes to school by bike. He passes by a police station, a library and a swimming pool（游泳池）.

图为人体呼吸系统组成示意图．请回答：

（1）呼吸系统由____ 和____ 组成．
（2）6____ 是呼吸系统的主要器官，它是____ 的场所．
（3）3____ 既是空气通道又是食物的通道．
（4）5是支气管，它进入肺后反复分支，在末端形成了许多____ ，其外壁有一层上皮细胞构成，外面缠绕着许多____ ，这有利于____ 与____ 进行气体交换．