单项选择题

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.