coronavirus pandemic, Dubai's Expo 2020 opens on Friday, pushing this city-state all-in on its bet of billions of dollars that the world's fair will boost its economy. The sheikhdom built what feels like an entire city out of what once were rolling sand dunes on its southern edges to support the fair, an outpost that largely will be disassembled after the six-month event ends in March.But questions about the Expo's drawing power in the modern era began even before the pandemic.