Задание 10 из ЕГЭ по английскому языку: задача 24

2. Some special features

3. Some dragonflies migrate

4. Excellent vision

5. Keeping them warm or cool

6. Masters of flight

7. Ancient insects

8. Risks of extinction

A. Long before the dinosaurs walked the Earth, dragonflies took to the air. If we could transport ourselves back 250 million years, we would immediately recognize the familiar sight of dragonflies flying in pursuit of prey. Ancient dragonflies may have been considerably larger than those we see today. A fossilized impression of a dragonfly wing, found in a coal mine in England, is the oldest known dragonfly specimen. This dragonfly lived 320 million years ago and had a wingspan of 8 inches.

B. Relative to other insects, dragonfly vision is extraordinarily good. The head consists almost entirely of two huge compound eyes, which gives the dragonfly nearly 360° vision. Each compound eye contains as many as 30,000 lenses, or ommatidia. A dragonfl y uses about 80% of its brain to process all this visual information. They can see a wider spectrum of colours than humans. This remarkable vision helps them to detect the movement of other insects and avoid collisions in flight.

C. Dragonflies can move each of their four wings independently. In addition to flapping each wing up and down, they can rotate their wings forward and back on an axis. This flexibility enables them to put on an aerial show like no other insect. Dragonflies can move straight up or down, fly backwards, stop and hover, and make hairpin turns, at full speed or in slow motion. A dragonfly can fly forward at a speed of 100 body lengths per second, or up to 30 miles per hour.

D. A number of dragonfly species are known to migrate. As with other organisms that migrate, dragonflies relocate to follow or find needed resources, or in response to environmental changes like cold weather. The globe skimmer is one of several species known to develop in temporary freshwater pools. Forced to follow the rains that replenish their breeding sites, the globe skimmer set a new insect world record when a biologist documented its 11,000 mile trip between India and Africa.

E. Fifty years ago there were twice as many ponds in Britain as there are today. The draining of agricultural land, filling in and pollution have all contributed to the disappearance of most countryside ponds. Canals have also suffered from pollution, especially by chemicals used on farmland draining into water. The loss of suitable fresh water habitats has affected dragonflies enormously and they are becoming increasingly rare. Some of dragonflies which can be found living only in the Norfolk Broads, is on the list of British endangered species of insects.

F. A dragonfly has two large compound eyes which take up most of its head. Dragonflies have long, delicate, membranous wings which are transparent and some have light yellow colouring near the tips. Their bodies are long and slender and they have short antennae. Dragonflies are very colourful. Some are red like the Comet Darner and yellow like the Emerald Darner. They can beat each pairs of wings together or separately and their rear wings can be out of phase with the front wings. Their wing beat is around 50–90 beats per second.

G. Dragonflies and butterflies possess two pair of wings. The butterfly’s wings are made up of two large pairs of wings each possessing a forewing and a hindwing. Butterflies can’t fly if the temperature of their body falls below 85 degrees and therefore need to sun themselves in order to warm up. Butterflies also have a pair of antennae with small receptors attached for smelling. Dragonflies have two pairs of wings that are transparent, rigid, straight, and have few veins. Unlike butterflies, dragonflies are adept at flying.