Task: Question Generation
Input (English): Express highways such as Hu–Ning, Ning–He, Ning–Hang enable commuters to travel to Shanghai, Hefei, Hangzhou, and other important cities quickly and conveniently. Inside the city of Nanjing, there are 230 km (140 mi) of highways, with a highway coverage density of 3.38 kilometres per hundred square kilometrs (5.44 mi/100 sq mi). The total road coverage density of the city is 112.56 kilometres per hundred square kilometres (181.15 mi/100 sq mi). The two artery roads in Nanjing are Zhongshan Road and Hanzhong. The two roads cross in the city centre, Xinjiekou.
Output (English): How many miles of highways are in Nanjing?