WhileIwentsightseein的精選

問題詳情：WhileIwentsightseeinginLondon,IvisitedtheLondonUnderground.Likemosttourists,Iwasveryinterestedinitasitisthe  61 (old)systemintheworld.Itisalsoverycomplex.Iwastoldthatthefirstpartoftheunderg...