Completar Frases Present Perfect vs Past SimpleVersión en línea review of the present perfect and past simple por Marta Teacher 1 become become have got started has weren't have have changed have have also have did paid were were changed evolved have have were have were created begun Since computers first introduced to the public in the early 1980's , technology a great deal . The first computers simple machines designed for basic tasks . They didn't much memory and they very powerful . Early computers often quite expensive and customers often thousands of dollars for machines which actually very little . Most computers separate , individual machines used mostly as expensive typewriters or for playing games . Times . Computers powerful machines with very practical applications . Programmers a large selection of useful programs which do everything from teaching foreign languages to bookkeeping . We are still playing video games , but today's games faster , more exciting interactive adventures . Many computer users on the Internet and communicating with other computer users around the world . We to create international communities online . In short , the simple , individual machines of the past into an international World Wide Web of knowledge .
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