A new computer system has been designed to stop ships sinking. The greatest danger 【21】______ a holed vessel is that flooding of its compartments will make the ship unstable enough to capsizE.It is estimated that nearly half the ships 【22】______ during the second world war capsized because of the loss of 【23】______ . Pacer systems of Burlington, Massachusetts, has now 【24】______ a system devised by a 【25】______ US Navy officer, Stephen Drabouski, which effectively thought out alternative strategies for the ship. The 【26】______ is programmed with every possible eventuality of flood damagE.【27】______ the actual damage is keyed into the computer the operator is told by the computer 【28】______ the implications are and what can be done to destabilize the vessel. Trials on the 'American aircraft carrier USS Midway' have 【29】______ that the reaction time to damage can be cut to a fiftieth. An incident was simulated in which the ship was 【30】______ by two missiles causing flooding to 30 compartments. It took 10 minutes 【31】______ receipt of the flood damage information in the damage control center to a full printout of damage effects, 【32】______ countermeasures and an assessment of the result of the countermeasures; In a re-run of the incident 【33】______ the computer program the damage control officer took four and a quarter hours to establish the 【34】______ of the damage and another four hours 【35】______ a decision could be taken on counter measures. 【36】______ the system can be used to provide damage control officers with advice, they do not, of course, have to 【37】______ the information. Quite often the' 【38】______ solution' will be unacceptable for operational reasons. When that happens the system can be asked for 【39】______ or the operator can interrogate the computer to find out what would happen 【40】______ the officer's own solution was put into action. 【21】 A.to B.on C.in D.for