职称英语考试

试题来源：2013年职称英语等级考试真题（理工类B级）
【单选题】

Putting Plants to Work
Using the power of the sun is nothing new. People have had solar-powered calculators and buildings with solar panels for decades. But plants are the real experts: They've been using sunlight as an energy source for billions of years.
Cells in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide, and water into sugars and starches, stored energy that the plants can use. This conversion process is called photosynthesis. Unfortunately, unless you're a plant, it's difficult and expensive to convert sunlight into storable energy. That's why scientists are taking a closer look at exactly how plants do it.
Some scientists are trying to get plants，or biological cells that act like plants，to work as very small photosynthesis power stations. For example，Maria Ghirardi of the National Renewable Energy Laboratory in Golden. Colo.，is working with green algae（水藻）. She’s trying to trick them into producing hydrogen instead of sugars when they perform photosynthesis. Once the researchers can get the algae working efficiently，the hydrogen that they produce could be used to power fuel cells in cars or to generate electricity.
The algae are grown in narrow-necked glass bottles to produce hydrogen in the lab. During photosynthesis，plants normally make sugars or starches.“But under certain conditions，a lot of algae are able to use the sunlight energy not to store starch，but to make hydrogen.”Ghirardi says. For example，algae will produce hydrogen in an airfree environment. It’s the oxygen in the air that prevents algae from making hydrogen most of the time.
Working in an airfree environment，however，is difficult. It’s not a practical way to produce cheap energy. But Ghirardi and her colleagues have discovered that by removing a chemical called sulfate（硫酸盐）from the environment that the algae grow in，they will make hydrogen instead of sugars，even when air is present.
Unfortunately, removing the sulfate also makes the algae's cells work very slowly, and not much hydrogen is produced. Still, the researchers see this as a first step in their goal to produce hydrogen efficiently from algae. With more work, they may be able to speed the cells' activity and produce larger quantities of hydrogen.
The researchers hope that algae will one day be an easy-to-use fuel source. The organisms are cheap to get and to feed, Ghirardi says, and they can grow almost anywhere： “You can grow them in a reactor, in a pond. You can grow them in the ocean. There's a lot of flexibility in how you can use these organisms.”
36. How do plants relate to solar energy？
    A  They have been using it for billions of years.
    B  They are the real experts in producing it.
    C  They have been a source of it.
    D  They have been used to produce it.
37. Scientists study how photosynthesis works because they want to
    A  improve the efficiency of it.
    B  turn plant sugars to a new form of energy.
    C  get more sugars and starches from plants.
    D  make green plants a new source of energy.
38. Algae are able to use solar energy to produce hydrogen when
    A  they are grown in narrow-necked bottles.
    B  there is no oxygen in the air.
    C  there is nenough oxygen in the air.
    D  enough starches is stored.
39. Researchers find it difficult to make algae produce hydrogen efficiently because
    A  it is hard to create an airfree environment.
    B  it is expensive to remove the sulfate from the environment.
    C  removing the sulfate slows down hydrogen production.
    D  the algae’s cells work slowly if there is no oxygen in the air.
40. What does Ghirardi say about algae？
    A  They can be a good energy source.
    B  They grow faster in a reactor.
    C  They will be planted everywhere.
    D  They are cheap to eat.

网考网参考答案：A、D、B、C、A
大数据分析：根据网考网与考试题库的统计分析，该试题：
31%的考友选择了A选项
14%的考友选择了B选项
29%的考友选择了C选项
26%的考友选择了D选项
考友解析与评论：
 · 这题不解，原来选A、D、B、C、A，感觉没错啊
 · 大家看教材，书上原话
 · 这题不解，原来选A、D、B、C、A，感觉挺好的