课后练习：

1. It's a privilege and an honor to participate ________the second season of conversations hosted ________the prestigious Harvard University Center for the Environment.

A. of; byB. in; inC. in; by

2. Access ________an economic and reliable supply of energy is essential to achieving greater prosperity and eradicating poverty, ________raising living standards in our communities, and to fueling economic and social development at home and abroad.

A. to; to B. in; toC. to; in

3. Oil meets nearly 40 percent of the world's total energy needs, coal and natural gas each account ________just under a quarter of total demand, hydropower and other alternatives for 8 percent, and nuclear energy for 6 percent of total energy supplies.

A. forB. atC. ofD. in

4. In addition, because the number of currently ________energy sources is so limited, we have to recognize that the options that are realistically ________to policymakers, producers and consumers are also relatively limited.

A. viable; unavailable B. unviable; available C. viable; available

5. In addition, because the number of currently viable energy sources is so limited, we have to recognize that the options that are ________available to policymakers, producers and consumers are also________limited.

A. relatively; realisticallyB. realistically; relatively

6. For example, ________power generation, there are a number of sources which contribute ________.

A. while it comes to; substantially

B. when it comes to; substantial

C. when it comes to; substantially

7. There are distinct reasons ________ oil is the fuel of choice in the all-important transportation sector.

A. whyB. whenC. where

8. Oil technologies ________ over almost 150 years, and continue to develop; its supplies are .

A. proved; abundant

B. have been proven; abundant

C. have been proven; abundantly (副词主要用于修饰动词和形容词，它不能做句子的表语)

9. Yes, ________a doubt,________there is more than enough oil remaining to meet the world's needs for many decades to come.

A. with; asB. without; asC. without; so

10.________ professional role or discipline, or the position we occupy along the energy value chain, each of us has a part to play in lightening energy's environmental footprint.

A. WhateverB. WhatC. Wherever

11. The EIA also projects that renewables, including hydroelectricity, ________more energy over the next quarter-century.

A. will generateB. will be generatingC. is generating

12. But even with anticipated technical advancements, ________source's share of global energy supplies will only increase by one percent over the next 25 year.

A. whichB. thisC. that

13. Hydrogen and fuel cells still have some way to go ________they are viable in the market, and face a number of technical and commercial obstacles that need ________.

A. before; to be resolvedB. after; to be resolved

C. before; to resolveD. being resolved

14. As an oil man, I not only welcome additional contributions from alternative fuels, ________I believe these contributions will be essential if we ________he growing needs of global energy consumers.

A. so; are to meetB. but; are to be metC. but; are to meet

15. No company or country, ________ large or capable, can face those challenges or seize those opportunities by working in isolation.

A. no matter whatB. no matter howC. no matter which