虽然大城市吸引了越来越多的人，但也带来了许多挑战，如交通堵塞和污染问题。
While big cities are attracting more and more people, they also bring many challenges, such as traffic jam and pollution.
一个麻省理工的研究者写文章指出这种趋势加重了一些问题，如日趋严重的地球轨道堵塞和正在增加的空间垃圾。
The MIT-based authors of the journal article note that the trend could exacerbate some problems, such as the growing congestion in earth orbit as well as the danger of spreading space debris.
沃尔沃的工程师们预计，车辆将可以彼此警告如湿滑路面等危险情况，一些汽车导航仪甚至已经可以相互警告交通堵塞了。
Volvo's engineers envision cars being able to warn each other of hazards such as slippery roads. Some GPS units already tip each other off about traffic jams.
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