Passage　2
Flu(which　is　short　for　influenza)　is　a　highly　contagious　disease,　the　cause　of　which　is　a　very　tiny　organism　known　as　a　virus.　Several　types　of　flu　are　recognized,　depending　on　the　type　of　virus　that　causes　the　disease.
When　people　catch　flu,　they　often　complain　of　a　headache　or　a　sore　throat.　They　usually　have　a　fever　and　their　temperature　rises　from　the　normal　37C　(98.6F)　to　about　39.5C　(103F).　Sometimes　a　person　has　a　dry　hacking　(猛烈地干咳)　cough　and　aching　joints.
Today　many　doctors　prescribe　drugs　that　fight　the　disease.　And　scientists　have　also　developed　vaccines　(疫苗)　that　help　to　prevent　it.　If　the　patient　has　proper　treatment,　and　complete　rest　in　bed,　the　virus　is　normally　beaten　within　a　week　to　ten　days.
How　does　flu　spread　so　quickly?　When　the　infected　person　breathes　out,　sneezes　or　coughs,　he　gives　out　droplets　(飞沫)　of　moisture　in　the　breath　from　his　mouth　or　nose.　These　remain　in　the　air　for　some　time.　Flu　viruses　are　present　in　these　droplets.　If　a　person　sneezes　in　a　crowed　or　poorly　ventilated　place,　such　as　a　lift,　viruses　can　easily　be　carried　from　an　infected　person　to　a　healthy　person.　This　is　known　as　droplet　infection.　The　healthy　person　will　breathe　in　the　viruses　given　out　by　the　infected　person.
Flu　can　often　cause　complications　in　breathing,　and　general　infection　of　the　lung.　With　elderly　and　weak　people,　these　added　complications　often　yield　serious　results.　The　virus,　if　not　properly　treated,　can　weaken　the　body　so　that　patient　may　develop　more　serious　illnesses,　such　as　pneumonia　(肺炎)　and　bronchitis　(支气管炎).
There　are　three　main　types　of　virus　that　cause　flu,　which　are　called　type　A,　B　and　C.　type　A　is　the　most　powerful　of　the　three,　and　undergoes　minor　changes　in　its　genetic　material　every　few　years.　The　new　form　of　the　virus　is　called　a　strain　(菌株).　The　new　strain　is　not　affected　by　the　current　vaccines.　It　is　said　to　be　"　resistant"　to　them.　So　doctors　must　be　continually　producing　new　vaccines　to　combat　the　new　strains　of　virus.
41.　The　types　of　flu　vary　with　__________.
○A.　the　character　of　organism
○B.　the　portal　of　entry
○C.　the　organ　involved
○D.　the　pathogenic　agents

42.　Today　vaccines　have　been　developed　and　used　for　_______　purposes.
○A.　curative
○B.　preventive
○C.　therapeutic
○D.　diagnostic
43.　The　transmitting　medium　for　flu　is　__________.
○A.　air
○B.　food
○C.　water
○D.　a　mosquito

44.　Flu　is　more　likely　to　affect　___________.
○A.　the　young
○B.　the　adults
○C.　the　elderly
○D.　the　new-born　infants

45.　The　most　dangerous　complication　of　flu　is　__________.
○A.　bronchitis
○B.　inflammation　of　the　lungs
○C.　emphysema
○D.　sinusitis