67.(A) Ever (B) As (C) Once (D) Already

76. Which of the following is implied about anthropologists before Boas? (A) They did not base their theories on observation. (B) They did not study other cultures. (C) They did not gather enough evidence for their theories (D) They did not agree on theoretical research methods Article C The tropical rainforests play a crucial role in sustaining life on our planet. They are vitally important to the environment. However, the rainforests around the world from Australia to Brazil are being depleted at a dramatic rate. Recent estimates are that deforestation has reduced the amount of tree cover on our planet by more than 50 percent. Forests are cut down for many reasons, but most of them are related to the increase in human population. A major contributing factor is the clearing of land for agriculture. Farmers cut down forests to cultivate crops or to provide grazing land for their livestock. When trees are cut down for agriculture, they are not replaced with new trees. Not only animal species, but also plants with as yet undiscovered potential medicinal uses are destroyed with a resulting decrease in biodiversity. The preservation of animal and plant species is essential for maintaining the future sustainability of life on our planet. A second cause of deforestation is the use of wood for construction and manufacturing, as well as for paper production. Legal and illegal logging in many countries has destroyed large areas of forest and **this** has led to a degradation of soil conditions. Trees not only provide shade and protection that keep soil moist, their roots also hold the soil together, preventing erosion. Land that has been cleared for cultivation easily becomes barren and more susceptible to damage from floods and droughts. Trees play an important role in absorbing greenhouse gases. Without trees, larger amounts of greenhouse gases enter the atmosphere and contribute to air pollution and global warming. Trees are also very important in the process of precipitation. The leaves of the trees contribute humidity to the atmosphere through the process of transpiration. Fewer trees mean that there is a reduction in humidity in the air, which affects not only the local ecosystem, but weather patterns globally, potentially harming agricultural production around the world.

67.
(A) Ever
(B) As
(C) Once
(D) Already

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67.(A) Ever(B) As(C) Once(D) Already

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67.
(A) Ever
(B) As
(C) Once
(D) Already