Complex sentence: The Kabul-Kandahar highway is 483-kilometer (300-mile) road that links Afghanistan's two largest cities, Kabul and Kandahar, and is a key portion of Afghanistan's national road system known as the "Ring Road".
Split into simpler sentences: The Kabul-Kandahar highway is a 483-kilometer (300-mile) road linking Afghanistan's two largest cities, Kabul and Kandahar. This highway is a key portion of Afghanistan's national road system or "Ring Road".