10．WAS the London Olympics a success？Many people hold different opinions．However one thing is certain，London could win a gold medal for hosting the"greenest"Games ever，BBC News reported．
Previous Olympic hosts have been criticized for the environmental damage they have caused through construction，waste．and transport．But things had to be different in London because seven years ago it bid for the Olympics through the concept of"a One Planet Olympics"．
What is most impressive is that London used the construction of the Olympic Park as an opportunity to clean up polluted areas-2 million tons of contaminated （被污染的） soil were removed and 200 old factory buildings，were torn down，according to sustainablebusiness．com．But that's not all-.99 percent of the debris （废瓦砾） were reused to build the Olympic Park．For example，part of the Olympic Stadium's roof is made from 2，500 tons of steel tubes recycled from old gas pipelines．
As well as using recycled materials，all venues were built with green building techniques．The Olympic Stadium is the lightest one ever built，which minimized the amount of steel and concrete needed．Also，the handball field has lighting pipes on the roof that reduce electricity use by 40 percent，according to sustainablebusiness．com．
The effort that London made to deal with waste also deserves praise．Water used for drinking and watering plants was from collected rainwater or recycled wastewater．In this way．about 30-40 percent less water was used in total．Waste food packages were either recycled or processed and turned into renewable energy．
As one of the best connected places in Europe，London tried to solve traffic jams by encouraging the use of public transport．For example，it had trains deliver half of the building materials，instead of cars，which greatly reduced carbon emissions．
The clean anti-doping （反兴奋剂） result also added to the greenness of the Games．The International Olympics Committee （IOC） said that the devices used this time were the most accurate and advanced．Only one athlete tested positive for a banned drug on the day of competing，which is why the IOC President，Jacques Rogge，has praised anti-doping efforts at the London Games．
51．To make the Olympic Park green，LondonD．
A．recycled 2 million tons of contaminated soil
B．removed 99 percent of the debris from the city
C．built the Olympic Stadium mostly with recycled materials
D．applied green building techniques to the construction work
52．The underlined word"minimized"in the fourth paragraph probably meansB
A．increased as much as possible
B．reduced as much as possible
C．made good use of
D．took little notice
53．What can we conclude from the article？C
A．The London Olympics cost less than the other Olympics ever held．
B．London has possessed the most advanced techniques to deal with waste．
C．Public transport is made good use of in London durIng the Olympic games．
D．The anti-doping result in the London Olympics turned out to be dissatisfactory．
54．Which of the following best shows the structure of the text？B
55．What is the best title of the passage？C
A．How to deal with the anti-doping
B．How to use recycled materials
C．London's green games
D．London's public transport．
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