Louis Pasteur 1822-1895
As a young man, Pasteur 1) studied at the École Nуrmale in Paris. Then at the age of just 32, he 2) (become) _______ a professor at the University of Lille. In 1856, Pasteur 3) (receive) _______ a visit from a man called Bigo who 4) (own) _______ a factory that 5) (make) _______ alcohol from sugar beet. He 6) (have) _______ a question for Pasteur: why 7) (the alcohol / turn / to acid?) _______ ? When this 8) (happen) _______, they 9) (not can) _______ use it and 10) (throw) _______ it away. Bigo 11) (ask) _______ Pasteur to find out the reason for this. At first, Pasteur 12) (not know) _______, but when he 13) (examine) _______ the alcohol under a microscope, he 14) (find) _______ thousands of tiny micro-organisms. He 15) (believe) _______ that they 16) (cause) _______ the problem. 17) (milk, wine and vinegar / behave / in the same way?) _______________________________? Other scientists 18) (disagree) _______ with him, and newspapers 19) (make) _______ fun of him. However, Pasteur 20) (continue) _______ with his work, he 21) (invent) _______ methods of testing his theory and 22) (prove) _______ that he was right. Later he 23) (work) _______ together with two doctors and 24) (develop) _______ vaccines for diseases such as anthrax and rabies.
10. Past Simple and Present Perfect
Past Simple versus Present Perfect
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Past Simple
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Present Perfect
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complete action which happened at a time in the past:
e.g. She left yesterday.
(When did she leave? Yesterday.)
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complete action which happened at a time in the past
e.g. Don has left for Madrid. (We don't know when he left; unstated time; he's now there or on his way there.)
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past action which is and happened at a definite past time not mentioned
e.g. I met John Lennon. (I won't meet him again; he's dead. – period of time finished)
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past action which is and happened at a definite past time not mentioned
e.g. I've spoken to Richard Gere. (I may speak to him again; he's alive. – period of time not finished yet)
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10.1 Read the text about climate change. Choose the correct form, A or B, to complete the sentence:
At the moment, scientists agree that the world's climate 1) B warmer over the past 50 years, but they disagree about the causes. Some believe that human activities 2) ___ climate change. They argue that for 1,000 or 2,000 years before 1850, when records 3) ___, the temperature was more or less stable. Short warm or cold periods 4) ___ during that time, but the climate always 5) ___ to the same level. However, since the Industrial Revolution, human beings 6) ___ more and more fossil fuels, such as coal and oil. In 1800 the atmosphere 7) ___ around 280 parts per million of carbon dioxide (CO2). Since then there 8) ___ an increase of about 3 l%. This extra carbon dioxide 9) ___ the world's temperature because of the greenhouse effect.
Other scientists disagree that human activities over the past 50 years 10) ___ global warming. They point out that volcanoes and other
natural processes 11) ___ CO2 into the atmosphere, and that human activity 12) ___ a rise in CO2 of only three per cent.
In 1999, 156 countries 13) ___ the Kyoto protocol, part of a United Nations agreement on climate change, which 14) ___ into force in 2005.They 15) ___ to reduce their emissions of CO2 and other greenhouse gases, although so far, some countries, such as the USA and
Australia, 16) ___ any action.
1. A became B has become
2. A caused B have caused
3. A began B have begun
4. A occurred B have occurred
5. A returned B has returned
6. A burned B have burned
7. A contained B has contained
8. A was B has been
9. A raised B has raised
10. A caused B have caused
11. A always released B have always released
12. A contributed B has contributed
13. A signed B have signed
14. A came B has come
15. A agreed B have agreed
16. A did not take B have not taken
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