From the four words or phrases choose the one that best completes the sentences.
The higher the content of carbon dioxide in the air, ______.
A.the more heat it retains
B.more heat it retains
C.it retains more heat
D.than it retains more heat

According to the passage, subsistence societies depend mainly on ____________.
A.agricultural products
B.nature's provision
C.farming methods
D.hunter-gatherers' tools

Which of the following would serve as the best title of the passage?
A.Hunter-gatherers: Always on the Move
B.Evolution of Humans' Farming Methods
C.Hunter-gatherers and Subsistence Societies
D.A Brief History of Subsistence Farming

According to the passage, studies of contemporary subsistence societies can provide a _________.
A.deeper insight into the dry-land farming
B.further understanding of modern subsistence societies
C.broader vision of prehistoric natural environments
D.further understanding of prehistoric times

From the four words or phrases choose the one that best completes the sentences.
The doctor insited that his patient ______.
A.that he not work too hard for three months
B.take it easy for three months
C.taking it easy inside of three months
D.to take some vacations for three months

Read the passage carefully, then choose the correct answers.
At present, people depend on unlimited energy to power their everyday lives. A wide range of energy-run devices and modern conveniences are taken for granted, and although it may seem that we will never be in danger of living without those conveniences, the fact is that many supplies of energy are dwindling rapidly. Scientists are constantly searching for new sources of power to keep modern society running. Whether future populations will continue to enjoy the benefit of abundant energy will depend on the success of this search.
Coal, oil, and natural gas supply modern civilization with most of its power. However, not only are supplies of these fuels limited, but they are a major source of pollution. If the energy demands of the future are to be met without seriously harming the environment, existing alternative energy sources must be improved or further explored and developed. These include nuclear, water, solar, wind, and geothermal power, as well as energy from new, nonpolluting types of fuels. Each of these alternatives, however, has advantages and disadvantages.
Nuclear power plants efficiently produce large amounts of electricity without polluting the atmosphere; however, they are costly to build and maintain, and they pose the daunting problem of what to do with nuclear wastes. Hydroelectric power is inexpensive and environmentally safe, but impractical for communities located far from moving water. Harnessing energy from tides and waves has similar drawbacks. Solar power holds great promise for the future but methods of collecting and –concentrating sunlight are as yet inefficient, as are methods of harnessing wind power.
Every source of energy has its disadvantages. One way to minimize them is to use less energy. Conservation efforts coupled with renewable energy resources, such as a combination of solar, water, wind, and geothermal energy and alternative fuels, such as alcohol and hydrogen, will ensure supplies of clean, affordable energy for humanity's future.
Which of the following is not true according to the passage?
A.The amount of fossil fuels in the world is limited.
B.Most alternative energy sources are environmentally friendly.
C.Hydroelectric power is impractical because of its being money consuming.
D.It is impossible to use wind power efficiently at present.

Read the passage carefully, then choose the correct answers.
At present, people depend on unlimited energy to power their everyday lives. A wide range of energy-run devices and modern conveniences are taken for granted, and although it may seem that we will never be in danger of living without those conveniences, the fact is that many supplies of energy are dwindling rapidly. Scientists are constantly searching for new sources of power to keep modern society running. Whether future populations will continue to enjoy the benefit of abundant energy will depend on the success of this search.
Coal, oil, and natural gas supply modern civilization with most of its power. However, not only are supplies of these fuels limited, but they are a major source of pollution. If the energy demands of the future are to be met without seriously harming the environment, existing alternative energy sources must be improved or further explored and developed. These include nuclear, water, solar, wind, and geothermal power, as well as energy from new, nonpolluting types of fuels. Each of these alternatives, however, has advantages and disadvantages.
Nuclear power plants efficiently produce large amounts of electricity without polluting the atmosphere; however, they are costly to build and maintain, and they pose the daunting problem of what to do with nuclear wastes. Hydroelectric power is inexpensive and environmentally safe, but impractical for communities located far from moving water. Harnessing energy from tides and waves has similar drawbacks. Solar power holds great promise for the future but methods of collecting and –concentrating sunlight are as yet inefficient, as are methods of harnessing wind power.
Every source of energy has its disadvantages. One way to minimize them is to use less energy. Conservation efforts coupled with renewable energy resources, such as a combination of solar, water, wind, and geothermal energy and alternative fuels, such as alcohol and hydrogen, will ensure supplies of clean, affordable energy for humanity's future.
It can be implied from the passage that ______.
A.most alternative energy sources have proven to be impractical
B.many alternative energy' sources. are environmentally hazardous
C.nuclear power solves one problem while creating others
D.solar and wind power are not promising for the future

Fill in the blanks with the correct answers.
Have you ever used a magnifying glass to make something melt or burn? If yes, you were using solar power! "Solar" is the Latin word for "sun" - and it's a powerful (26)________ of energy. In fact, the sunlight that shines on the Earth in just one hour could meet world energy demand (27)__________ an entire year! We can use solar power in two different ways: as a heat source, and as an energy source. People have used the sun as a heat source for thousands of years. Families in ancient Greece built their homes to get the most sunlight (28)________ the cold winter months. In the 1830s, explorer John Herschel used a solar collector to cook food during an adventure in Africa. You can even try this at home! (29)___________, we can use solar collectors for heating water and air in our homes. If you've seen a house with big shiny panels (30)____________, that family is using solar power.
(30)
A.on the top
B.on the roof
C.on the bottom
D.on the peak

A typical feature of both modern and prehistoric hunter-gatherers is that ____________.
A.they don't have a healthy and balanced diet
B.they live in the forests for all their life
C.they don't have a strong sense of community
D.they often change their living places

Choose the word or phrase that needs correcting.
The world's rain forests are being cut down at the rate on 3,000 acres per hour.
A.rain
B.are being
C.on
D.per hour