听力原文： A few months ago, millions of people in London heard alarms all over the town. Emergency services, the Fire Department, the Police, hospitals. And ambulances stood by, ready to go into action. In railway and underground stations, people read notices and maps, which told them where to go and what to do in an emergency. This was Exercise Flood Call, to prepare people for a flood emergency. London wasn't flooded yet, but it is possible that it would be. In 1236 and in 1663, London was badly flooded. In 1928, people living in Westminster, the heart of London, drowned in floods. And in 1953, one hundred people, living on the eastern edge of the London suburbs were killed again in floods. At last, Greater London Council took action to prevent this disaster from happening again. Though a flood wall was built in the 1980s, Londoners still must be prepared for the possible disaster. If it happens, 50 underground stations will be under water. Electricity, gas and phone services will be out of action. Roads will be submerged. It will be impossible to cross any of the bridges between North and South London. Imagine: London will look like the famous Italian city, Venice. But this Exercise Flood Call didn't cause panic among Londoners. Most people knew it was just a warning. One lady said, "It's a flood warning, isn't it？ The water doesn't look nigh to me."
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A. The heart of London was flooded.
B. An emergency exercise was conducted.
C. 100 people in the suburbs were submerged.
D. One of the bridges between North and South London collapsed.