Fill in the correct verb tense of the verbs in brackets. Choose between past simple and present perfect
Since computers were first introduced to the public in the early 1980's, technology ___________ (1. change) a great deal. The first computers ___________ (2. be) simple machines designed for basic tasks. They ___________ (3. not have) much memory and they ___________ (4. not be) very powerful. Early computers were often quite expensive and customers often ___________ (5. pay) thousands of dollars for machines which actually ___________ (6. do) very little. Most computers ___________ (7.be) separate, individual machines used mostly as expensive typewriters or for playing games. Times ___________ (8. change). Computers ___________ (9. become) powerful machines with very practical applications. Programmers ___________ (10. create) 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 ___________ (11. become) faster, more exciting interactive adventures. Many computer users ___________ (12. also get) on the Internet and ___________ (13. begin) communicating with other computer users around the world. We ___________ (14. start) to create international communities online. In short, the simple, individual machines of the past ___________ (15. evolve) into an international World Wide Web of knowledge.