Helping things to grow

Need has to are may must cannot must is able to need must can must

Complete the sentences with these verbs.

Exercises

Модальные глаголы, выражающие разную степень уверенности и определенности(degrees of certainty).

использование	глагол	пример
Используется для выражения уверенности (в настоящем или в целом).	must, can`t, couldn`t	That must be our hotel. This can`t\couldn`t be our hotel.
Используется для выражения уверенности (в прошлом).	must, can`t, couldn`t+perfect infinitive	She must have been in a lot of pain. She can`t\couldn`t have taken the whole pack of pain-killers!
Используется для выражения вероятности тех или иных действий (в настоящем, будущем или в целом).	should, ought to	You ought to\should feel better in a few days.
Используется для выражения вероятности тех или иных действий (в прошлом).	should, ought to+perfect infinitive	He ought to\should have arrived ages ago. I wonder why he didn`t.
Используется для выражения возможности тех или иных действий (в настоящем, будущем или для ситуации в целом).	could, may, might	If I were you I would not touch this snake. It may\could\might be dangerous.
Используется для выражения возможности тех или иных действий(в реальном прошлом).	could, may, might +perfect infinitive	He could\may\might have written thas letter last week.
Используется для выражения возможности тех или иных действий (в гипотетическом прошлом).	could, might+perfect infinitive	We took a taxi to the airport, otherwise we could\might have been late.

Growing plants ….. sunlight, carbon dioxide gas from the air, and water from the soil. ….. they get anything else? Certainly. Plants ….. get other things from the soil, especially potassium, nitrogen and phosphorus, if they are to thrive.

Soil contains some of these materials, but farmers ….. get good yields of crops if they do not put extra amounts on the fields when they sow the seeds in spring.

Wheat, barley and oats take a lot of nitrogen from the soil, and so the farmer ….. use a lot of nitrogen fertilizers (ammonium, sulphate or nitrate) when he plants these crops. Another way of putting nitrogen into soil is by growing beans, peas and clover. There are bacteria living in the roots of these plants that take nitrogen gas out of the air and change it into nitrogen fertilizer in the soil. After growing clover - for the farm animals - the farmer ….. grow a good crop of wheat the next year in the same fields, and he ….. not put any nitrogen fertilizer in the soil.

There are tiny plants (plankton) growing on the surface of the sea. What ….. they got for their growth? They ….. the same materials for growth as the plants we ….. see on land. There is plenty of potassium in sea water, but not much nitrogen or phosphate, so if we add fertilizers there will be a bigger growth of these tiny plants.

But why ….. we care about plants growing in the sea? Small sea plants in turn are eaten by fish. If there are more plants (plankton) there will in time be more and bigger fish for us to catch and eat. The scientists ….. to increase the fish in the open sea.

Дата добавления: 2014-01-04