阅读下面的短文．并根据短文后的要求答题。
Since 1850．the temperature of Earth’s surface has increased about 0.6°C．Scientists predict it may warm much more by the end of this century．Who’s turning up the heat? Well, it seems that we are! Some of this global warming may be natural．However，nearly all scientists now agree that most of it is due to peoples actions．Over the past 150 years, we've added huge amounts of certain gases, especially carbon dioxide（CO2）to the air．These gases can keep heat near Earth's surface，so more carbon dioxide means more heat is kept near Earth's surface．Global warming may change the weather in ways that lead to more severe storms，floods and droughts．
We add carbon dioxide to the air when we burn things, especially fossil fuels．Fossil fuels are energy sources formed from the remains of plants and animals that lived millions of years ago．Coal，oil，and natural gas are all fossil fuels．People in the United States and other countries started bunting large amounts of fossil fuels more than a century ago．The amount d fossil fuels being burned each year has been increasing worldwide．The more we burn，_____________________．
What can we do to help? Nowadays to live a low-carbon life is quite popular in the world． Low-carbon means to reduce the amount of carbon dioxide．Saving energy and reusing are the key words. In fact, even the simplest everyday activities can make our lives low-carbon．
1．What problem can global warming cause?（根据短文内容回答问题）
2．What are fossil fuels?（同上）
3．请将第一段中的划线句子翻译成汉语。
4．请根据第二段内容，将最后一个句子补充完整。
The more we bum，_____________________________________________.
5．请写出日常生活中的一种“低碳”行为（用英语写一个句子）。