Task: Question Generation
Input (English): In the 1960s, the first Nanjing Yangtze River Bridge was completed, and served as the only bridge crossing over the Lower Yangtze in eastern China at that time. The bridge was a source of pride and an important symbol of modern China, having been built and designed by the Chinese themselves following failed surveys by other nations and the reliance on and then rejection of Soviet expertise. Begun in 1960 and opened to traffic in 1968, the bridge is a two-tiered road and rail design spanning 4,600 metres on the upper deck, with approximately 1,580 metres spanning the river itself. Since then four more bridges and two tunnels have been built. Going in the downstream direction, the Yangtze crossings in Nanjing are: Dashengguan Bridge, Line 10 Metro Tunnel, Third Bridge, Nanjing Yangtze River Tunnel, First Bridge, Second Bridge and Fourth Bridge.
Output (English): How many more bridges have been built since the first one was completed?