問題詳情

Human activity often interferes with the natural world. So many imbalances in ourecosystems are blamed, and __7__ so, on human activity. We tend to think of nature as selfregulating and perfect, __8__ we humans would stay out of the way. Recently, a team ofscientists found a striking example __9__.An estimated 70,000 hippos in Tanzania and Kenya’s Mara River dumped nearly 52,300metric tons of poop, killing fish, sometimes by the thousands. Scientists observed the dead fish__10__ up on the shores of the Mara each time the river rose up a few feet. Nine sets of fishkills were observed within five years. Rangers were aware of the problem, but assumed it wascaused by pesticides sprayed by local farmers upstream. Scientists Chris Dutton and AmandaSubalusky conducted experiments and discovered the real cause. Fish were choking to death on第 2 頁，共 13 頁hippo poop. Every day, around 4,000 hippos were __11__ about 8,500 kilograms of waste intothe Mara along a short 100-kilometer stretch of river. The river is so dense with hippo poop thatdipping a net into the water for just a few seconds coats it with feces almost immediately.Hippo pools are flooded by __12__ heavy rains known as flushing flows. Polluted watersdisturb the river bottom and reduce oxygen levels downstream, killing the fish. The scientistsconfirmed their theory by adding hippo poop to bottled water. Oxygen levels fell dramatically.Reduced oxygen levels in the river is a problem with implications for African aquatic life, notjust in Kenya and Tanzania, __13__ it was discovered. Many kinds of ecosystems depend onclean water from rivers. Could human intervention improve this situation before it’s too late?
7.
(A) scarcely
(B) randomly
(C) rightfully
(D) accidentally

參考答案

答案：C
難度：適中0.555556
統計：A(3),B(1),C(5),D(0),E(0)

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