UNITS 6 and 7
Date: 2015-10-07; view: 417.
REVISION AND DEVELOPMENT
Write a summary of the text in your own words using your plan, and the sentences you've written out and condensed. Omit all unnecessary details.
Write out of the text all the sentences expressing the main idea(s) of each logical part taking into account all the changes that you've made.
Read the text again, divide it into logical parts and entitle them.
15. Condense the sentences of the text if possible using 1) infinitive constructions; 2) participle constructions; 3) gerundial constructions. One of the sentences is given to you as an example:
Example: It is known that carbon occurs in two crystalline forms.
Carbon is known to occur in two crystalline forms.
1. Look through the following text and find the answers to the given questions:
1. Who eats plants?
2. What is the form of carbon in the Earth's crust?
3. What energy is used by green plants and algae and what do they do with it?
4. What are the ways of forming carbon dioxide?
5. How are human activities now estimated?
6. Why is it hard now to estimate them?
It is known, that carbon, like water, cycles from the Earth into the atmosphere and back again. Green plants and algae use the sun's energy to convert carbon dioxide (and water) into carbohydrates. The plants are eaten by animals, including people and fish, who exhale carbon dioxide. It was discovered that carbon dioxide is also formed by decomposition of dead animals and animal wastes by microorganisms. The carbon dioxide passes into the atmosphere and is again used for photosynthesis. An equilibrium also exists between carbon dioxide in the atmosphere and dissolved carbon dioxide and H2CO3 in oceans and lakes. In addition it was estimated that much carbon is stored in the Earth's crust in the form of fossil fuels — coal, petroleum, and natural gas — and in the form of limestone and coral. Since the middle of the nineteenth century, it has been observed that the production of carbon dioxide by the combustion and the decomposition of limestones is increasing rapidly. In addition, it has been proved that destruction of tropical forests is reducing the quantity of carbon dioxide used up by photosynthesis. Human activities have now reached a scale where interference with the natural carbon cycle may well be significant. The longest continuous records of the concentration of CO2 in the atmosphere unfortunately were made only in 1958, and therefore it's hard to be sure how harmful human activities have been since that time.