exhaust

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.

现代发动机的设计旨在减少有害废气的排放。

Modern engines are designed to reduce harmful ___exhaust emissions.

汽车废气是造成城市空气污染的重要因素。

Car ___exhaust fumes contribute significantly to urban air pollution.