5.9. Заполните пропуски в предложениях модальными глаголами can, may или must: 1.One … identify many plants by studying their leaves.
2.Only plants … create food, animals obtain food only by eating plants or other animals.
3.A leaf … manufacture food by means of photosynthesis, otherwise a plant will die.
4.The structure of a leaf … be different in various species.
5.A leaf … capture the sun's energy and build complex molecules from raw materials.
6.You … see the midrib of the blade without a microscope.
7.Dicot leaves … be either simple or compound.
8.The leaf edge … be indented in various ways.
9.Eucalyptus trees grow in California, but these broad-leavedevergreens … not compete successfully with deciduous trees where the climate turns cold.
10.You … not touch that plant! It's poisonous.
11.You … take those flowers, I'll bring some more.
12.Whatever man does to his forests, he … consider the whole ecosystem, including the soil in its relationship to vegetation.
13.Larches are one of the few species that … stand the climate close to the frigid, empty tundra.
14.A plant … adjust itself to the environment in which it grows if it is to survive.
5.10. Замените модальные глаголы can,may иmust эквивалентами to be able to, to have to, to be to, should, to be allowed to:
1.Sphagnum moss can absorb up to seven times its volume in water.
2.Students may use the new equipment that was installed in the laboratory of forest research.
3.The wide-spreadingleaves of fernscan collect a large amount of light for photosynthesis.
4.The tree must become dormant to survive the winter cold.
5.Conifers can photosynthesize all year long, even when water, light, and heat are at low levels.
6.People must think about the ways of preventing pollution if they want to live in a healthy environment.
7.Seeds can survive long periods of dormacy and still germinate and grow normally when conditions are favourable.
8.There is a danger of forest fires now. May people enter this forest?
9.Animals cannot create food as green plants do.
10.Scientists must not forget that some plants used in folk medicine help against even fatal illnesses.
11.The members of the expedition must leave at night to get to the forest early in the morning.