Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 36 to 42.

Arid regions in the southwestern United States have become increasingly inviting playgrounds for the growing number of recreation seekers who own vehicles such as motorcycles or powered trail bikes and indulge in hill-climbing contests or in carving new trails in the desert. But recent scientific studies show that these off-road vehicles can cause damage to desert landscapes that has long-range effects on the area’s water-conserving characteristics and on the entire ecology, both plant and animal. Research by scientists in the western Mojave Desert in California revealed that the compaction of the sandy arid soil resulting from the passage of just one motorcycle markedly reduced the infiltration ability of the soil and created a stream of rain runoff water that eroded the hillside surface. In addition, the researchers discovered that the soil compaction caused by the off-road vehicles often killed native plant species and resulted in the invasion of different plant species within a few years. The native perennial species required many more years before they showed signs of returning. The scientists calculated that roughly a century would be required for the infiltration capacity of the Mojave soil to be restored after being compacted by vehicles

According to the passage, the damage to plants is _______.

A. unnoticeable

B. superficial

C. long-lasting

D. irreparable

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 36 to 42.

Arid regions in the southwestern United States have become increasingly inviting playgrounds for the growing number of recreation seekers who own vehicles such as motorcycles or powered trail bikes and indulge in hill-climbing contests or in carving new trails in the desert. But recent scientific studies show that these off-road vehicles can cause damage to desert landscapes that has long-range effects on the area’s water-conserving characteristics and on the entire ecology, both plant and animal. Research by scientists in the western Mojave Desert in California revealed that the compaction of the sandy arid soil resulting from the passage of just one motorcycle markedly reduced the infiltration ability of the soil and created a stream of rain runoff water that eroded the hillside surface. In addition, the researchers discovered that the soil compaction caused by the off-road vehicles often killed native plant species and resulted in the invasion of different plant species within a few years. The native perennial species required many more years before they showed signs of returning. The scientists calculated that roughly a century would be required for the infiltration capacity of the Mojave soil to be restored after being compacted by vehicles

According to the passage, what happens when the soil is compacted?

A. Little water seeps through

B. Better roads are made

C. Water is conserved

D. Deserts are expanded

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 36 to 42.

Arid regions in the southwestern United States have become increasingly inviting playgrounds for the growing number of recreation seekers who own vehicles such as motorcycles or powered trail bikes and indulge in hill-climbing contests or in carving new trails in the desert. But recent scientific studies show that these off-road vehicles can cause damage to desert landscapes that has long-range effects on the area’s water-conserving characteristics and on the entire ecology, both plant and animal. Research by scientists in the western Mojave Desert in California revealed that the compaction of the sandy arid soil resulting from the passage of just one motorcycle markedly reduced the infiltration ability of the soil and created a stream of rain runoff water that eroded the hillside surface. In addition, the researchers discovered that the soil compaction caused by the off-road vehicles often killed native plant species and resulted in the invasion of different plant species within a few years. The native perennial species required many more years before they showed signs of returning. The scientists calculated that roughly a century would be required for the infiltration capacity of the Mojave soil to be restored after being compacted by vehicles

What is happening to the desert hillsides?

A. The topsoil is being eroded

B. The surface is being irrigated

C. There are fewer types of plants growing on them

D. There are fewer streams running through them

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 36 to 42.

Arid regions in the southwestern United States have become increasingly inviting playgrounds for the growing number of recreation seekers who own vehicles such as motorcycles or powered trail bikes and indulge in hill-climbing contests or in carving new trails in the desert. But recent scientific studies show that these off-road vehicles can cause damage to desert landscapes that has long-range effects on the area’s water-conserving characteristics and on the entire ecology, both plant and animal. Research by scientists in the western Mojave Desert in California revealed that the compaction of the sandy arid soil resulting from the passage of just one motorcycle markedly reduced the infiltration ability of the soil and created a stream of rain runoff water that eroded the hillside surface. In addition, the researchers discovered that the soil compaction caused by the off-road vehicles often killed native plant species and resulted in the invasion of different plant species within a few years. The native perennial species required many more years before they showed signs of returning. The scientists calculated that roughly a century would be required for the infiltration capacity of the Mojave soil to be restored after being compacted by vehicles

What is the main topic of the passage?

A. Problems caused by recreational vehicles

B. Types of off-road vehicles

C. Plants of the southwestern desert

D. The increasing number of recreation seekers

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 36 to 42.

Arid regions in the southwestern United States have become increasingly inviting playgrounds for the growing number of recreation seekers who own vehicles such as motorcycles or powered trail bikes and indulge in hill-climbing contests or in carving new trails in the desert. But recent scientific studies show that these off-road vehicles can cause damage to desert landscapes that has long-range effects on the area’s water-conserving characteristics and on the entire ecology, both plant and animal. Research by scientists in the western Mojave Desert in California revealed that the compaction of the sandy arid soil resulting from the passage of just one motorcycle markedly reduced the infiltration ability of the soil and created a stream of rain runoff water that eroded the hillside surface. In addition, the researchers discovered that the soil compaction caused by the off-road vehicles often killed native plant species and resulted in the invasion of different plant species within a few years. The native perennial species required many more years before they showed signs of returning. The scientists calculated that roughly a century would be required for the infiltration capacity of the Mojave soil to be restored after being compacted by vehicles

According to the passage, what is being damaged?

A. Motorcycles

B. The desert landscape

C. Roads through the desert

D. New plant species

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 36 to 42.

Arid regions in the southwestern United States have become increasingly inviting playgrounds for the growing number of recreation seekers who own vehicles such as motorcycles or powered trail bikes and indulge in hill-climbing contests or in carving new trails in the desert. But recent scientific studies show that these off-road vehicles can cause damage to desert landscapes that has long-range effects on the area’s water-conserving characteristics and on the entire ecology, both plant and animal. Research by scientists in the western Mojave Desert in California revealed that the compaction of the sandy arid soil resulting from the passage of just one motorcycle markedly reduced the infiltration ability of the soil and created a stream of rain runoff water that eroded the hillside surface. In addition, the researchers discovered that the soil compaction caused by the off-road vehicles often killed native plant species and resulted in the invasion of different plant species within a few years. The native perennial species required many more years before they showed signs of returning. The scientists calculated that roughly a century would be required for the infiltration capacity of the Mojave soil to be restored after being compacted by vehicles

It can be inferred that which of the following people would probably be most  alarmed by the scientists’ findings?

A. Historians

B. Mapmakers

C. Farmer

D. Ecologists

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 25 to 29. Fill in the appropriate word in question 26

Environmental pollution

Environmental pollution is a term that refers to all the ways by which man pollutes his surroundings. Man dirties the air with gases and smoke, (25) _______the water with chemicals and other substances, and damages the soil with (26) _______ many fertilizers and pesticides. Man also pollutes his surroundings in various other ways. For example, people ruin natural beauty by (27) _______ junk and litter on the land and in the water. They operate machines and motor vehicles that fill the air with disturbing noise.

Environmental pollution is one of the most serious propblems facing humankind today. Air, water, and soil are necessary to the survival of all living things. Badly polluted air can cause illness, and (28) _______ death.Polluted water kills fish and other (29) _______ life. Pollution of soil reduces the amount of land that is available for growing food.

A. extreme

B. too

C. such

D. all

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 25 to 29. Fill in the appropriate word in question 25

Environmental pollution

Environmental pollution is a term that refers to all the ways by which man pollutes his surroundings. Man dirties the air with gases and smoke, (25) _______the water with chemicals and other substances, and damages the soil with (26) _______ many fertilizers and pesticides. Man also pollutes his surroundings in various other ways. For example, people ruin natural beauty by (27) _______ junk and litter on the land and in the water. They operate machines and motor vehicles that fill the air with disturbing noise.

Environmental pollution is one of the most serious propblems facing humankind today. Air, water, and soil are necessary to the survival of all living things. Badly polluted air can cause illness, and (28) _______ death.Polluted water kills fish and other (29) _______ life. Pollution of soil reduces the amount of land that is available for growing food

A. disposing

B. filling

C. using

D. making

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 25 to 29. Fill in the appropriate word in question 28

Environmental pollution

Environmental pollution is a term that refers to all the ways by which man pollutes his surroundings. Man dirties the air with gases and smoke, (25) _______the water with chemicals and other substances, and damages the soil with (26) _______ many fertilizers and pesticides. Man also pollutes his surroundings in various other ways. For example, people ruin natural beauty by (27) _______ junk and litter on the land and in the water. They operate machines and motor vehicles that fill the air with disturbing noise.

Environmental pollution is one of the most serious propblems facing humankind today. Air, water, and soil are necessary to the survival of all living things. Badly polluted air can cause illness, and (28) _______ death.Polluted water kills fish and other (29) _______ life. Pollution of soil reduces the amount of land that is available for growing food.

A. therefore

B. consequently

C. even

D. just