一阵响亮的嘎嘎声从汽车的排气管传来。

A loud rattling sound came from the car's ___exhaust.

排气管排出的烟雾加剧了城市的雾霾问题。

The fumes from the ___exhaust were contributing to the city's smog problem.

机修工发现排气管上有一道裂缝，正是泄漏的源头。

The mechanic identified a crack in the ___exhaust as the source of the leak.