1、What is said to be a key challenge for cities prone to floods?A.Eliminating their root cause.B.Forecasting flood risks accurately.C.Identifying the cities 'geological features.D.Finding out the changing climate patterns.2、For what purpose does Derek Loftis collect the data of ordinary citizens during high tides?E.To validate his hypothesis about the gravity of floods.F.To determine the frequency of high tides causing floods.G.To improve his mathematical flooding model.H.To see the feasibility of his project on flooding.3、What does the passage say is Derek Loftis 's mission?I.To study the consequences of high tides on flooded areas.J.To teach local citizens how to collect data of incoming floods.K.To forecast rapid floods in real time.L.To classify the flooding data processed.4、What did Loftis and his colleagues do to obtain data about water height and movement?M.They set up Internet-connected water-level sensors.N.They tracked the rising tides with video-cameras.O.They used newly-developed supercomputing facilities.P.They observed the direction of water flow on the spot.