昨天的答案：

1. D   2. S   3. D   4. S   5. S   6. D   7. S   8. D

今天学习PHOT和LUC两个词根。

PHOT comes from the Greek word for "light." Photography uses light to create an image on film or paper, and a photocopy is an image made by using light and tiny electrically charged ink particles.

photoelectric. Involving an electrical effect produced by the action of light or other radiation.

例句：They wanted to avoid the kind of smoke detector that uses radioactive materials, so they've installed the photoelectric kind instead.

他们想避免使用放射性材料的烟雾探测器，所以他们已经安装了光电类型的。

The photoelectric effect occurs when light (or similar radiation such as X-rays) falls on a material such as a metal plate and causes it to emit electrons. The discovery of the photoelectric effect led to important new theories about matter (and a Nobel Prize for Albert Einstein). Photoelectric cells, or photocells, are used in burglar-alarm light detectors and garage-door openers (both employ a beam of light that is broken when something moves across it), and also to play soundtracks on movie film (where a light beam shines through the soundtrack encoded on the film and is "read" by the photocells).

photovoltaic. Involving the direct generation of electricity when sunlight or other radiant energy falls on the boundary between dissimilar substances. (such as two different semiconductors).

例句：Photovoltaic technology is being applied to thin film that can produce as much energy as solar cells while using far less semiconducting material.

光伏技术正应用于薄膜，它可以产生与太阳能电池一样多的能量，同时使用的半导体材料少得多。

The -voltaic part of photovoltaic comes from the name of Alessandro Volta, inventor of the electric battery. Thus, unlike photoelectric cells, which use electricity for certain small tasks, photovoltaic (or PV) cells actually produce electricity. Solar cells, the standard type of photovoltaic cells (often called simply photocells), operate without chemicals and with no moving parts to create energy directly from sunlight. Much research is now being done on creating an alternative technology--solar film, which could be stuck onto almost any surface, or possibly even sprayed on.

photon. A tiny particle or bundle of radiant energy.

例句：The idea that light consists of photons is difficult until you being to think of a ray of light as being caused by a stream of tiny particles.

光线由光子组成的想法是很难实现的，直到你将光线想象为由微小粒子流引起的光线。

It was Albert Einstein who first theorized that the energy in a light beam exists in small bits or particles, and scientists today know that light sometimes behaves like a wave (somewhat like sound or water) and sometimes like a stream of particles. The energies of photons range from high-energy gamma rays and X-rays down to low-energy infrared and radio waves, though all travel at the same speed. The amazing power of lasers is the result of a concentration of photons that have been made to travel together in order to hit their target at the same time.

photosynthesis. The process by which green plants use light to produce organic matter from carbon dioxide and water.

例句：Sagebrush survives in harsh climates because it's capable of carrying on photosynthesis at very low temperatures.

灌木蒿在恶劣的气候条件下生存下来，是因为它能够在非常低的温度下进行光合作用。

The Greek roots of photosynthesis combine to produce the basic meaning "to put together with the help of light." Photosynthesis is what first produced oxygen in the atmosphere billions of years ago, and it's still what keeps it there. Sunlight splits the water molecules (made of hydrogen and oxygen) held in a plant's leaves and releases the oxygen in them into the air. The leftover hydrogen combines with carbon dioxide to produce carbohydrates, which the plant uses as food--as do any animals or humans might eat the plant.

LUC comes from the Latin noun lux, "light," and the verb lucere, "to shine or glitter." In ancient Rome, Lucifer, meaing "Light-bearer," was the name given to the morning star, but the name was eventually transferred by Christians to Satan. This tradition, which dates back to the period before Christ, said that Lucifer had once been among the angels but had wanted to be the great light in the sky, and for his pride had been cast out of heaven and thus became the opponent of everything good.

lucid. (1) Very clear and easy to understand. (2) Able to think clearly.

例句：On his last visit he had noticed that his elderly mother hadn't seemed completely lucid.

在他上次访问时，他注意到他年迈的母亲似乎并没有完全清醒。

Mental lucidity is easy to take for granted when we're young, though alcohol, drugs, and psychological instability can confuse the mind at any age. We all hope to live to 100 with our mental abilities intact, which is entirely possible; avoiding the condition called dementia (which includes the well-known Alzheimer's disease) often involves a combination of decent genes, physical and mental activity, and a good diet. Writing lucidly, on the other hand, can take a lot of work at any age; you've probably had the experience of trying to read a set of instructions and wondering if the writer even grew up speaking English.

elucidate. To clarify by explaining; explain.

例句：A good doctor should always be willing to elucidate any medical jargon he or she uses.

一位好医生应该总是愿意阐明他使用的任何医学术语。

The basic meaning of elucidate is "to shed light on." So when you elucidate, you make transparent or clear something that had been murky or confusing. Elucidation of a complex new health-care policy may be a challenge. Elucidation of the terms of use for a credit card may be the last thing its provider wants to do. The physicist Carl Sagan had a gift for elucidating astronomical science to a large audience, his lucid explanations making clear how stars are born and die and how the universe may have begun.

lucubration. (1) Hard and difficult study. (2) The product of such study.

例句：Our professor admitted that he wasn't looking forward to reading through any more of our lucubrations on novels that no one enjoyed.

我们的教授承认，他不希望再读一遍我们对没有人喜欢的小说的看法。

Lucubration came to mean "hard study" because it originally meant study done by lamplight, and in a world without electric lights, such study was likely to be the kind of hard work that would only a dedicated student like Abe Lincoln would make a habit of. The word has a literary feel to it, and it's often used with a touch of sarcasm.

translucent. Partly transparent; allowing light to pass through without permitting objects beyond to be seen clearly.

例句：Architects today often use industrial glass bricks in their home designs, because translucent walls admit daylight while guarding privacy.

如今的建筑师经常在他们的家居设计中使用工业玻璃砖，因为半透明的墙壁在保护隐私的同时允许太阳光入室。

With its prefix trans-, meaning "through," translucent describes material that light shines through without making anything on the other side clearly visible, unlike a transparent material. Frosted glass, often used in bathroom windows, is translucent, as is stained glass. Red wine in a crystal goblet, when held before a candle in a dark corner of a quiet restaurant, usually proves to be translucent as well.

Quiz:

Match the definition on the left to the correct word on the right:

1. involving the interaction of light with matter.          a. lucubration

2. production of carbohydrates                                  b. photoelectric

3. clarify                                                                     c. translucent

4. passing light but only blurred images                    d. elucidate

5. elemental particle                                                  e. photovoltaic

6. brightly clear                                                          f. photosynthesis

7. hard study                                                             g. photon

8. using light to generate electricity                           h. lucid