72. What is the main purpose of this passage?
(A) to propose solutions to Taiwan’s pollution problem
(B) to advise readers to stay indoors
(C) to explore different kinds of air pollution
(D) to focus on indoor pollution

exhaust
1. to make someone extremely tired
使筋疲力竭；使疲憊不堪
The long journey exhausted the children.
長途旅行後，孩子們疲憊不堪。
I've exhausted myself with all that cleaning.
打掃累得我筋疲力盡。

2. to use something completely
用完；花光；耗盡
How long will it be before the world's fuel supplies are exhausted?
再過多長時間地球上的燃料就耗盡了？
I'm afraid he's exhausted my patience.
恐怕我對他已經失去耐性了。 We seem to have exhausted this topic of conversation (= we have nothing new to say about it).
這個話題我們好像已經沒有甚麼好談的了。
 3. the waste gas from an engine, especially a car's, or the pipe the gas flows through
（引擎排出的）廢氣；（尤指汽車的）尾氣；排氣管
Car exhaust is the main reason for the city's pollution.
汽車排出的廢氣是造成城市污染的主要原因。
 sulfur dioxide 二氧化硫
carbon monoxide一氧化碳
nitrogen oxide一氧化氮
chemical vapors 化學氣相沉積
smog 霧霾

資料來源：劍橋詞典