Perfect tenses.
1. Match the sentences with the explanations.
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1. present perfect – present result of a past event
| a. Before he left the company he had been putting together a software package.
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2. present perfect – present situation that started in the past
| b. People have been using computers for different purposes - both good and bad.
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3. present perfect - unfinished period of time
| c. I was sure I had deleted all the client records.
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4. present perfect continuous - action in progress from the past up to the present
| d. The update process had been running for 20 minutes when the computer suddenly crashed.
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5. present perfect continuous - emphasis on the duration of time
| e. I have already checked all our records today and it’s only lunchtime.
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6. present perfect continuous – actions repeated over a period of time
| f. He had installed the new software and then restarted the computer.
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7. past perfect – emphasis on the action that happened before another past event/moment
| g. The antivirus has been running for over an hour and there is still more than 60% left.
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8. past perfect + verb of thinking
| h. The latest data input has overwritten the old information.
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9. past perfect continuous – situation that was in progress up to a certain point in the past
| i. He goes there once a week to check computer systems. He has been going there for several months already.
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10. past perfect continuous - emphasis on the duration of time
| j. The new operation system has been installed on our computers since we hired this engineer.
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2. Put the verbs in brackets into the correct perfect tense form.
- A solid working knowledge of productivity software and other IT tools (become) a basic foundation for success in virtually any career nowadays.
- Before the new program superseded the earlier one our work (be) much slower.
- With this system we (eliminate) all possibilities of error.
- The latest version of our award-winning image-editing software (increase) in popularity for the last several weeks.
- The brand new, friendly drag-and-drop interface (allow) me to get more productive.
- The capabilities of the PC (change) greatly since the introduction of electronic computers.
- The file (download) for more than an hour and it still shows only 18 percent!
- They (re-design) the software adding wizards and tutorials that explain complex procedures and their sales increased dramatically.
- Older people (suffer) from computer anxiety in recent years.
- The tech support officer thought the client (press) the wrong key.
- As I (save) this file in the wrong directory I couldn’t find it when I needed it.
- The maintenance engineers (try) to identify the cause of the system failure for several hours before they managed to.
- The use of computers in all spheres of life (increase) over the last few decades.
- Before the invention of home computers and the Internet people (spend) more time outdoors.
- By the end of the 20th century metal wires (be) replaced by fiber-optic ones.
- Human beings always (seek) for a machine to help them make their lives easier and at last computer was created.