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. 练习：
1.Paragraph l . 2.Paragraph 3 . 3.Paragraph 5 . 4.Paragraph 6 . 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
5.Unlike traditional lighting, LEDs do not give out heat so .
6.Edison's bright invention is likely to be outdated because .
7.Something unexpected happened during Bower's experiment
when .
8.Over one quarter of energy consumption for lighting could be saved by 2025 if .
A traditional lighting is less durable and dearer B a laser excited the quantum dots C America adopted LEDS D graduate students work hard E quantum dot mixtures are magic F it is more efficient
How we form first impression
1 We all have first impression of someone we just met. But why? Why do we form an opinion about someone without really knowing anything about him or her – aside perhaps from a few remarks or readily observable traits.
2. The answer is related to how your brain allows you to be aware of the world. Your brain is so sensitive in picking up facial traits, even very minor difference in a how a person’s eyes, ears, nose, or mouth are placed in relation to each other make you see him or her as different. In fact, your brain
continuously processes incoming sensory information – the sights and sounds of your world. Theses incoming “signals” are compared against a host of “memories” stored in the brain areas called the cortex （大脑皮层）system to determine what these new signals “mean”.
3 If you see someone you know and like at school, your brain says “familiar and safe”. “If you see someone new, it says, “new—potentially threatening”. Then your brain starts to match features of this stranger with other “known” memories. The height, weight, dress, ethnicity, gestures and tone of voice are all matched up. The more unfamiliar the
characteristics, the more your brain may say, “This is new. I don’t like this person.” Or else, “I am intrigued.” Or your brain may perceive a new face but familiar clothes, ethnicity, gestures – like your other friends; so your brain says: “I like this person.” But theses preliminary “impressions” can be dead wrong.
4 When we stereotype people, we use a less mature form of thinking (not unlike the immature thinking of a very young child) that makes simplistic and categorical impressions of others. Rather than learn about the depth and breadth of people –
their history, interest, values, strengths, and true character – we categorize them as jocks, geeks, or freaks.
5 However, if we resist initial stereotypical impressions, we have a chance to be aware of what a person is truly like. If we spend time with a person, hear about his or her life, hopes, dreams,and become aware of the person’s character, we use a different, more mature style of thinking—and the most complex areas of our cortex, which allow us to be humane.
Screen test
1. Every year millions of women are screened with X-rays to pick up signs of breast cancer. If this happens early enough, the disease can often be treated successfully. According to a survey （调查）published last year, 21 countries have screening programmes. Nine of them, including Australia, Canada, the US and Spain, screen women under 50.
2. But the medical benefits of screening these younger women are controversial（有争议的）, partly because the radiation（辐射） brings a small risk of inducing cancer. Also, younger women must be given higher doses of X-rays because their breast tissue（组织） is denser.
3. Researchers at the Polytechnic University1 of Valencia analysed the effect of screening more than 160,000 women at 11 local clinics. After estimating the women’s cumulative dose of radiation, they used two models to calculate the number of extra cancers this would cause.
4. The mathematical model recommended by Britain’s National Radiological Protection Board (NRPB) predicted that the screening programme would cause 36 cancers per 100,000 women, 18 of them fatal. The model preferred by the UN Scientific Committee on the Effects of Atomic Radiation led to a lower figure of 20 cancers.
5. The researchers argue that the level of radiation-induced cancers is “not very significant” compared to the far larger number of cancers that are discovered and treated. The Valencia programme, they say, detects between 300 and 450 cases of breast cancer in every 100,000 women screened.
6. But they point out that the risk of women contracting cancer from radiation could be reduced by between 40 and 80 percent if screening began at 50 instead of 45, because they would be exposed to less radiation. The results of their study, they suggest, could help “optimize the technique” for breast cancer screening.