問題詳情

請依下文回答第 41 題至第 45 題  One of the hidden glories of Victorian engineering is proper drains. Isolating a city’s effluent and shipping it awayin underground sewers has probably saved more lives than any medical procedure except vaccination. But out of sightis out of mind. And that, together with the inherent yuckiness of the subject, means that many old sewers have beenneglected and are in dire need of repair. If that repair does not come in time, the result is noxious and potentiallyhazardous. All this neglect, though, makes it hard to know where best to apply the sticking-plasters. So MarkHernandez of the University of Colorado, Boulder, and his team have been looking for an easily measurable signal thatsomething is about to go wrong.  A candidate, Dr. Hernandez suspected, is hydrogen sulphide. This is one of the gases that make sewage stink.Though not itself damaging to a pipe’s fabric, it can be converted by certain species of bacteria into sulphuric acid.Pretty well all sewage smells of hydrogen sulphide, though, so for it to be a useful telltale you need to know just howmuch is a sign of trouble. Dr. Hernandez and his colleagues therefore collected samples from 36 sewers in variousstates of decay and started looking.  One of their interests was in the mixture of bacteria found in pipes in different states of repair. Rather than culturingthese, a process to which not all species are amenable, they ran them through a mass DNA screening that shows upeverything in a sample. They also measured the acidity of the sewage soaked into the pipe wall near where the samplewas collected and recorded the concentrations in the air there of hydrogen sulphide, methane and carbon dioxide.
41 According to this article, what is damaging to the sewer pipe’s fabric? 
(A)hydrogen sulphide  
(B)bacteria 
(C)sulphuric acid  
(D)sticking plasters 

參考答案

答案：C
難度：適中0.534884
統計：A(9),B(7),C(23),D(3),E(0)

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