[填空题]Among all visible lights, red light has (long)（）and violet the shortest wavelength.

[填空题]Ultroviolet light has long been used in water-treatment plants to help with virus killing. As long as the water is clear enough not to absorb the rays, (36) it to a discharge lamp will destroy the DNA of viruses and (37) that could otherwise cause illness when (38) . Now a group of researchers have developed an industrial-scale solar-driven purification system that removes not only bugs but also chemical (39)
The first of their (40) has been built as demonstration project. The researchers wanted to clean the water that they use to cool their (41) engines. This cooling water (42) gets contaminated both with rocket fuel and with (43) produced by the burning of the fuel.
The trick the researchers use to boost the cleansing action of ultraviolet is to add a light-activated catalyst(催化剂) to the waste water. (44) . After a complex series of reactions, water gets pure enough to be

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It has long been the subject of speculation among the police and criminologists: what would happen if all the officers who now spend so much of their time taking statements, profiling criminals and moving pieces of paper around were suddenly put on the streets Crime figures released by London’s Metropolitan Police this week provide the best answer yet.
Following the bombings of July 7th and 21st, thousands of police officers materialised on London’s pavements, many of them sporting brightly coloured jackets. Drawn from all over the city, they were assigned to guard potential targets such as railway stations. The police presence was especially heavy in the bombed boroughs: Camden (which was struck three times), Hammersnrith and Fulham, Lamheth, Tower Hamlets, Westminster and the City of London.
The show of force did not just scare off terrorists. There was less crime in July than in May or June, which As unusual: the warmer month tends to bring out crim
A. the trends which can be tracks
B. the deployment of the blue line
C. the overwhelming presence of criminals in London
D. the number of the days of terrorist attacks