News about natural disasters, including volcanoes, storms and earthquakes, is updated daily. Besides, global warming is causing heat waves to become more frequent, pushing the limits of human survival in the hottest regions on Earth. Recent record-breaking temperatures in various parts of the world have highlighted the dangers caused by extreme heat and thrown light on the challenges that lie ahead.
When faced with extreme heat, the human body depends on its natural cooling mechanisms（机制）to keep a safe temperature. However, very high heat overpowers these mechanisms, putting human lives at risk. Research shows that the body's ability to cool through sweating（出汗）begins to decrease at $35°\mathrm{C}$. Being in such conditions can put pressure on the heart and cause body temperatures to rise uncontrollably, creating the greatest risk to older people and those with diseases.
Recently, scorching temperatures have broken records across the globe. China experienced a historic high of nearly $126°\mathrm{F}$. America reached $128°\mathrm{F}$. The Middle East hit $133°\mathrm{F}$, nearing the limit of what humans can stand.
These extreme heat events offer a look at the future, as global warming continues to push temperatures. The frequency of dangerously high temperatures has more than doubled since 1979, according to research in 2020.
The seriousness and widespread nature of ongoing heat waves highlight that climate change is a global problem with far-reaching effects. Human activities, such as the burning of fossil fuels（化石燃料）, have greatly contributed to the rise in heat-trapping greenhouse gases, leading to more heat waves and other extreme weather events. It is high time to cut down on greenhouse gases and choose cleaner renewable energy sources. International cooperation and leadership are necessary to reduce the effect of climate change on our planet and protect the well-being of future generations.
4. What is the text mainly about? （）
A. The dangers of cool waves.
B. The causes of natural disasters.
C. The introduction of the hottest regions on Earth.
D. The exploration of the rising heat's effect on humans.
5. What does the research find about human sweating? （）
A. It controls the cooling mechanisms.
B. It becomes less effective at $35°\mathrm{C}$.
C. It increases heart efficiency in heat.
D. It improves cooling in all conditions.
6. What is the data in Paragraph 3 about? （）
A. Temperature limits that humans can stand.
B. Frequencies of dangerously high temperatures.
C. Global average temperatures at different time periods.
D. Record-breaking temperatures in specific countries and regions.
7. What is the author's main purpose in writing the last paragraph? （）
A. To call on stopping using fossil fuels.
B. To call on ignoring extreme weather events.
C. To call on working internationally to address climate change.
D. To call on cutting down on cleaner renewable energy.
energy.

语篇解读 本文是一篇说明文。文章主要介绍了全球变暖导致的极端高温现象及其对人类的影响。
4. D 主旨大意题。根据全文内容,特别是第一段最后一句可知,文章主要介绍了全球变暖导致的极端高温现象及其对人类的影响。故选 D。
5. B 细节理解题。根据第二段中的“Research shows that the body's ability to cool through sweating (出汗) begins to decrease at $35°C$.”可知,关于人类出汗的研究发现,在 $35°C$ 时,出汗降温的效果会减弱。故选 B。
6. D 细节理解题。根据第三段内容可知,第三段的数据是关于特定国家和地区的创纪录高温。故选 D。
7. C 推理判断题。根据最后一段最后一句可推知,作者写最后一段的主要目的是呼吁国际社会合作应对气候变化。故选 C。