AS SOON AS MARY WILL GRADUATE NEXT MONTH, SHE WILL RETURN TO HER...

30.

As soon as Mary will graduate next month, she will return to her home town.

A.

will graduate

^B.

soon as

^C.

home town

^D.

return

VIII.

Read the passage carefully and choose the correct answer.

Plants and animals hold medicinal, agricultural, ecological value. Endangered species must be

protected and saved so that future generations can experience their presence and value.

Plants and animals are responsible for a variety of useful medications. In fact, about forty percent of

all prescriptions written today are composed from the natural compounds of different species. These

species not only save lives, but they contribute to a prospering pharmaceutical industry worth over $40

billion annually. Unfortunately, only 5% of known plant species have been screened for their medicinal

values, although we continue to lose up to 100 species daily. The Pacific yew, a slow-growing tree found

in the ancient forests of the Pacific Northwest, was historically considered a "trash" tree. However, a

substance in its bark was recently identified as one of the most promising treatments for ovarian and

breast cancer. Additionally, more than 3 million American heart disease sufferers would die within 72

hours of a heart attack without digitalis, a drug derived from the purple foxglove.

There are an estimated 80,000 edible plants in the world. Humans depend upon only 20 species of

these plants, such as wheat and corn, to provide 90% of the world's food. Wild relatives of these

common crops contain essential disease-resistant material. They also provide humans with the means to

develop new crops that can grow in inadequate lands such as in poor soils or drought-stricken areas to

help solve the world hunger problem. In the 1970s, genetic material from a wild corn species in Mexico

was used to stop a leaf fungus that had previously wiped out 15% of the U.S. corn crop.

Plant and animal species are the foundation of healthy ecosystems. Humans depend on ecosystems such

as coastal estuaries, prairie grasslands, and ancient forests to purify their air, clean their water, and

supply them with food. When species become endangered, it is an indicator that the health of these vital

ecosystems is beginning to unravel. The U.S. Fish and Wildlife Service estimates that losing one plant

species can trigger the loss of up to 30 other insect, plant and higher animal species. The northern

spotted owl, listed as threatened in 1990, is an indicator of the declining health of the ancient forests of

the Pacific Northwest. These forests are the home to over 100 other old-growth dependent species,

which are at risk due to decades of unsustainable forest management practices. Pollution off the coast of

Florida is killing the coral reefs along the Florida Keys, which serve as habitat for hundreds of species of

fish. Commercial fish species have begun to decline, causing a threat to the multi-million dollar tourism

industry, which depends on the quality of the environment.