1. The surface of the Earth is 70% … to an average depth of over 4 kilometers.
2. In the dry parts of Africa there is little… water.
3. The presence of an oil film with a thickness of only one thousandth of a millimeter may reduce the rate at which … is transferred from air to water.
4. Water is a vital resource because of its physical and chemical …
5. Heat accumulation in the hydrosphere in summer time and heat withdrawal in winter time make milder the … of the Earth.
6. … destructs rocks, dissolves inorganic compounds and carries them over great distances.
7. River water has some … for self-purification, but some pollutants are objectionable because they overload the self-purification processes of the river.
8. Most municipal water found in a city or community today has been treated …
c) in a wrong way
9. The water emerging from some … may have fallen as rain many decades, hundreds, thousands or even some millions of years ago.
a) surface water
c) deep ground water
10. People began to build large scale water projects only in the … century.
11. Water taken from its natural sources contains … harmful elements.
a) a lot of
c) not many
12. … and rock layers naturally filter the ground water to a high degree of clarity before it is pumped to the treatment plant.
a) treatment systems
13. … doesn’t need screening before other purification steps.
b) surface water
c) lake water
14. Water from rivers may be stored in bankside reservoirs for periods between a few days and many … to allow natural biological purification to take place.
15. Water service is …
a) the main pipe delivering water to a potable water system
b) a water dealing organization
c) water treatment
16. Water used for any purpose … returned to the potable water supply.
a) should be
b) shouldn’t be
c) could be
17. Every day the world shortage of fresh water …
18. The idea of using iceberg as a source of fresh water is…
c) not new
19. All devices used to treat or convey … water must be protected against contamination.
20. Natural water sources can wholly … the need for water in the town.
Учебный элемент 1 (УЭ-1).
My Future Profession
I. Vocabulary Work.