Question

With petroleum reserves (石油儲量) decreasing, the search is on to replace gas with a cleaner，greener alternative. Though much eco－talk has centered on biofuels from corn and soybeans, the biofuel that looks more likely to replace petroleum comes from a most unlikely source: algae(藻類)．

Algae, like corn, soybeans, and other crops, grow via photosynthesis(光合作用) and can be processed into fuel oil. However, they yield 30 times more energy than land crops such as soybeans, according to the U．S. Department of Energy. Many algae species also can grow in saltwater and polluted water—while corn and soy require arable land and fresh water that will be in short supply as the world's population balloons.

“If you replaced all the diesel(柴油) in the U．S. with soy biodiesel, it would take half the land mass of the U．S. to grow those soybeans，” says Matt Caspari, chief executive of Aurora Biofuels, a Berkeley, Calif－based private firm that specializes in algae oil technology. On the other hand, the Energy Department says that if algae fuel replaced all the petroleum fuel in the United States, it would require 15,000 square miles, which is a few thousand miles larger than Maryland (12,407 square miles), the 42nd state in land area.

Another bonus: Because algae can be grown just about anywhere in a closed space, they're being tested at several power plants across the nation as a carbon absorber. Smokestack emissions (煙囪排放物) can be pumped directly into the ponds, feeding the algae while keeping greenhouse gases out of the atmosphere.

Although processing technology for algae fuel－also known as “oilgae” in some environmentalist circles—is improving, it's still years away from reaching your local gas pump. “It's just a question of cost, because no large－scale facilities have been built yet，” Caspari says.

1. The underlined word “yield” in Paragraph 2 can be replaced by ________.

A. control         B. require

C. produce         D. grow

2. Compared with corn and soybeans, algae________.

A. may pollute water and soil

B. can grow in poor conditions

C. provide much less energy

D. need more special care

3. According to Paragraph 3, one of the advantages of algae fuel is that________.

A. it can be used more widely

B. it is more easy to produce

C. it needs much less land

D. it costs much less money

4. What do we learn about algae from Paragraph 4?

A. Algae help protect the environment.

B. People can grow algae anywhere.

C. Fish can get more oxygen from algae.

D. Algae produce less waste.

5. What does the passage mainly talk about?

A. Environmental protection.

B. Biofuels from corn and soybeans.

C. The false hope of biofuels.

D. A promising oil alternative.

Answer 1

1. 解析：選C。詞義理解題。此處根據(jù)這句話的意思可以推出它們生產(chǎn)的能量比大豆之類的農作物要多30倍。故選C。

2. 解析：選B。細節(jié)推理題。根據(jù)第二段第三句的“...can grow in saltwater and polluted water”和“...require arable land fresh water...”可知，玉米和大豆需要有良好的環(huán)境才能生長，而藻類在較差的環(huán)境下也能夠生長。

3. 解析：選C。細節(jié)理解題。根據(jù)第三段最后一句“On the other hand... the 42nd state in land area”可知，如果藻類燃料全部代替美國的石油燃料，所需土地比馬里蘭州的面積多一些，而該州面積僅居全美國42位。聯(lián)系本段第一句的“...it would take half the land mass of the U．S. to grow those soybeans...”可知，生產(chǎn)藻類燃料僅需很少的土地。

4. 解析：選A。推理判斷題。根據(jù)第四段第二句“Smokestack emissions can...of the atmosphere”可知，煙囪排放物能夠直接排入養(yǎng)殖著藻類的池塘，既向藻類提供了養(yǎng)料，又防止了溫室氣體污染大氣。可見，藻類對保護環(huán)境有利。

5. 解析：選D。主旨大意題。本文介紹了一種頗具前景的藻類能源，重點分析了這種新能源的優(yōu)勢。注意第一段第一句的關鍵詞alternative。