下面的短文后有2项测试任务：(1)第23～26题要求从所给的6个选项中为第1、3、5、6段每段选择1个最佳标题；(2)第27～30题要求从所给的6个选项中为每个句子确定1个最佳选项。 LED Lighting 1 An
accidental discovery announced recently has taken LED lighting to a new level,
suggesting it could soon offer a cheaper, longer-lasting alternative to the
traditional light bulb. The breakthrough adds to a growing trend that is likely
to eventually make Thomas Edison’s bright invention obsolete. LEDs are already
used in traffic lights, flashlights, and architectural lighting. They are
flexible and operate less expensively than traditional lighting.
2 Michael Bowers, a graduate student at Vanderbilt University, was
just trying to make really small quantum dots, which are crystals generally only
a few nanometers big. Quantum dots contain any where from 100 to 1,000
electrons. They’re easily excited bundles of energy, and the smaller they are,
the more excited they get. Each dot in Bower’s particular batch was
exceptionally small, containing only 33 or 34 pairs of atoms. 3
When you shine a light on quantum dots or apply electricity to them, they
react by producing their own light, normally a bright, vibrant color. But when
Bowers shined a laser on his batch of dots, something unexpected happened. He
was surprised when a white glow covered the table. The quantum dots were
supposed to emit blue light, but instead they were giving off a beautiful white
glow. 4 Then Bowers and another student got the idea to
stir the dots into polyurethane and coat a blue LED light bulb with the mix. The
lumpy bulb wasn’t pretty, but it produced white light similar to a regular light
bulb. 5 LEDs produce twice as much light as a regular 60
watt bulb and burn for over 50,000 hours. The Department of Energy estimates LED
lighting could reduce U.S. energy consumption for lighting by 29 percent by
2025. LEDs don’t emit heat, so they’re also more energy efficient. And they’re
much harder to break. 6 Quantum dot mixtures could be
painted on just about anything and electrically excited to produce a rainbow of
colors, including white. The main light source of the future will almost surely
not be a bulb. It might be a table, a wall, or even a fork.
A. LED Lighting Is Not Mature B. LED Lighting
Will Replace Traditional Lighting C. Almost Everything Could Be
the Main Light Source in the Future D. LED Lighting Has Many
Advantages E. Bowers Made an Unexpected Discovery
F. LED Light Bulbs Look Lumpy Paragraph 5 ______.