Поставьте глагол в правильную форму .
1. In early times people (to begin) domesticating wild animals .
2. I think the farmer (to increase) the yields of crops next year.
3.The scientists from our laboratory ( to present ) interesting reports at the conference recently.
4. Last year the farmers (not to rely ) on feeds from pastures and ( to grow ) additional crops for their livestock .
5. The cow ( convert ) large quantities of different grasses into milk which ( to be ) a valuable product .
6. As our agronomist (to recommend ) we ( to spread ) manure on this field now.
7. People ( to keep ) domesticated animals either in barns or on pastures .
8. The production of dairy product constantly (to increase ) in Russia at present.
9. What animals (to use ) people as draft animals in the 18 th century ?
10. For many centures people in Africa (to breed ) camels but even now a white camel (to be ) an exotic animals .
11. Last week the farmers (to keep ) swine on pastures .
12. Poultry also ( to convert ) feed efficiently into protein and (to provide ) people with meat and eggs .
13. If any species in the food chain ( to disappear ) ,there ( to be ) a disbalance in the whole ecosystem .
14. As soon as the environment of a species or a population ( to develop ) in an unfavourable way ,it ( to cause ) an ecological crisis.
15. If ecologists ( not / to make ) soil and water analyses,they ( not / to be able ) to estimate the environmental polution.