Read the article and choose a heading for each paragraph from the list below. There is one extra heading which you do not need to use. A. An old problem with serious consequences. B. Two new approaches, but can they solve the problem? C. A potentially tragic error. D. But are they here to stay? E. Experts say “Bring back maths!” F. Old methods are no longer satisfactory. G. We couldn't live without them. Our lives depend on computers. They control our money, transport, and our exam results. Yet their programme are now so complex that no one get rid of all the mistakes. 1.______________________ Life without computers has become unimaginable. They are designed to look after so many boring but essential tasks – from microwave cooking to flying across the Atlantic – that have become dependent on them. 2. _____________________ However, as demands placed on computers grow, so have the number of incidents involving computer errors. Now computer experts are warning that the traditional ways of building computer systems are just not good enough to deal with complex tasks like flying planes or maintaining nuclear power stations. It is only a matter of time before a computer-made catastrophe occurs. 3. _____________________ As early as 1889, a word entered the language that was to become all too familiar to computer scientists: a “bug”, meaning mistake. For decades, bugs and “debugging” were taken to be part of every computer engineer's job. Everyone accepted that there would always be some mistakes in any new system. But “safety critical” systems that fly planes, drive trains or control nuclear power stations can have bugs that could kill. This is obviously unacceptable. 4.______________________ One way to stop bugs in computer system is to get different teams of programmes to work in isolation from each other. That way, runs the theory, they won't all make type of mistake when designing and writing computer codes. In fact, researches shows that programmes think alike, have the same type of training – and make similar mistakes. So, even if they work separately, mistakes can still occur. Another technique is to produce backup systems that start to operate when the first system fails. This has been used on everything from the space shuttle to