职称英语综合类阅读理解的基础训练题(2)

　　There is no vaccine to prevent dengue and no specific medicine to treat it, so the only defense is eradication of the mosquitoes that carry it and measures to protect people from mosquito bites.

　　But hope is offered by research being carried out at the Southwest Foundation for Biomedical Research in San Antonio, which relies on very special mice.

　　The small white animals with pink eyes are kept in a special isolated room so that they will not be exposed to any bacteria or germs that might infect them. They have been altered to be susceptible to human diseases.

　　Lead researcher Rebecca Rico-Hesse says the mice have been modified or humanized by an infusion of stem cells taken from human umbilical cords that were discarded at local hospitals. We have basically reconstituted the human immune system in these mice and it is only because they have these immune system cells that they can get infected and show symptoms of dengue fever, she said.

　　By infecting these humanized mice with strains of the dengue virus, investigators can study how the disease takes hold and what factors might cause the more serious and often deadly dengue hemorrhagic fever.

　　A recent report co-authored by Rico-Hesse and her colleague Javier Mota shows for the first time why some strains of dengue virus are more severe than others. In this report, we present results of eight different virus strains and we show that the ones that have been associated with the more severe epidemics and the ones that cause hemorrhagic fever in patients are actually of a specific genetic variant, she said.

　　Lab workers infect the mice artificially with the virus, keeping precise records of how much virus and what type of virus is used. But natural transmission of dengue by mosquitoes involves certain proteins the insects inject into the skin, something that Rico-Hesse says is missing when mice are artificially infected in the lab.

　　If you are just, you know, injecting it in with a syringe, you are missing out on all those salivary gland factors and all the things that happen during a natural infection that might either speed up the infection rate or decrease the infection rate. And we also need to know how many mosquitoes it takes to infect a humanized mouse, she said.

　　Rico-Hesse and her colleagues are breeding mosquitoes in the laboratory to test various strains of the dengue virus transmitted to the mice by mosquitoes.

　　Although effective vaccines or antiviral drugs for dengue may still be a long way off, researchers here say they are making important steps that they hope will one day minimize the suffering and death caused by the illness

　　1.Which statement is correct according to Paragraph 1

　　A.Dengue fever can be eradicated by mosquitoes.

　　B.Strong effect of certain medication can cure dengue fever.

　　C.By killing all the mosquitoes in the world, we can prevent dengue fever.

　　D.Scientists have invented a vaccine that can prevent dengue fever

　　正确答案:C

　　2.The special mice used in the lab test

　　A.have red eyes.

　　B.are kept in an ordinary open room.

　　C.are put in the room with lots of mosquitoes.

　　D.have been altered so that they can easily infected by human diseases

　　正确答案:D

　　3.According to the report, the virus strains that cause the more severe dengue and hemorrhagic fever are actually

　　A.of a specific genetic variant..

　　B.from a special mosquito.

　　C.invented in the lab.

　　D.killable with a specific genetic variant

　　正确答案:A

　　4.Which statement is true according to the passage

　　A.Lab workers inject into the mice the fever virus with a syringe .

　　B.The umbilical cords used in modifying the immune system of the mice are from live humans.

　　C.The artificial infection of virus has exactly the same effect as the natural one.

　　D.Rico-Hesse and her colleagues are raising mosquitoes as their pets.

　　正确答案:A

　　5.What is the authors attitude to the future of the researchers work

　　A.Optimistic.

　　B.Pessimistic.

　　C.Objective.

　　D.Sarcastic

　　正确答案:C