Interfering with nature

O n the whole, our dare (1) efforts to control other species in the world have been a fail (2). If we had left things alone, the threat posed by pests like rats would have probable (3) never been so serious. For thousands of years we have been persist (4) in transferring species world (5) for one or another reason. But have we always achieved our object (6) or have we often done more bad than good?

For example, origin (7) rabbits were introduced into Australia as a source of food, but they multiple (8) at such a tremendous rate that they had to be destruction (9). Toads were introduced into the Pacific islands to provide

feed (10) for lizards, the latter themselves having been introduced to kill rats,

but the poison presence (11) in the toads’ bodies killed the number (12) lizards instead. In Britain, American grey squirrels were initial (13) introduced just to look pretty, and as a result Britain’s native species, the red squirrel, is now threatened with extinct (14).

5. Выберите подходящее слово из предложенных двух вариантов.

Invaders

Invasives take a staggering tall/toll (1) on the world’s economy. They cost the US alone 140 billion dollars a year. In the old West, cattlemen used to battle sheepherders over grazing/gazing (2) land. Today there’s a new enemy – a Eurasian weed called leafy spurge that overwhelms/ overworks (3) native grasses. Cows hate spurge, while sheep love it, so ranchers have put the old rival/rivalry (4) to rest for good.

Organisms labeled/libeled (5) “invasive” range from scarce/scary (6) – West Nile virus – to harmless ones. People have brought many exotic species/spices (7) into new environments for use as food, decoration or pets. Other species have hitched rides/raids (8) with cargo shipments. Some are benign/binary (9). But many make themselves too much at home, wreaking ecological havoc/helix (10).

6. Выберите подходящее слово из предложенных двух вариантов.

Unwelcome gifts

Brought from Asia as a royal gift/gain (1) to the Hawaiian king over a century ago, axis deer today are simply a royal pane/pain (2). Thousands inhabit/inhibit (3) the islands, stripping/striping (4) vegetation, speeding erosion, and causing car racks/wrecks (5). Another pest, the coqui frog, arrived occasionally/accidentally (6) on imported Caribbean plants. The frogs’ loud, incessant mature/mating (7) calls drive Hawaiians wild – though not with love.

Invasives are not like other forms of pollution/pollutants (8). They don’t stop spreading when you stop releasing/relieving (9) them. They grow.

Taro has been Hawaiian steeple/staple (10) for hundreds of years, but golden apple snail, introduced 15 years ago to be raised/risen (11) and sold for food, never found a market, taking a liking/likelihood (12) to taro instead.

Transported to North America in ship ballast water the Eurasian bivalve (Zebra mussel) is crowding out native/naked (13) clams and mussels. It has caused economic havoc in the Great Lakes, where it reaches densities/dentistry (14) high enough to clog water intake/input (15) pipes.

7. Образуйте соответствующее однокоренное слово.