PassageTwo
Questions26to30arebasedonthefollowingpassage.
Doctorshavelongknownthateatingfishhelpsprotectagainstheartdisease.
Whattheydon’tknowiswhyfisharebeneficial.Foryearstheyfigureditwasasimplequestionofsubstitution:
folkswhoreplaceredmeatwithfisharenaturallycuttingdowntheirintakeofsaturated(饱和的)fat.Butagrowingbodyofevidencecollectedoverthepast30yearssuggestsfishcontainhealthfulelementscalledomega-3fattyacids.
Omega-3fattyacidsbelongtoagroupofcompoundsknownaspolyunsaturatedfats.
Thesefatsserveastherawmaterialforawholehostofessentialstructuresinthebody,
frombraincellstomolecules(分子)thatregulatebloodpressure.
Sinceourbodiescannotmanufacturetheirownsupplyofomega-3s,wehavetogetthemfromthefoodweeat,mostlyfromfishbutalsofromplantsourceslikesoybeans(大豆).
TheAmericanHeartAssociationhasrecommendedthateveryoneeattwo85-gservingsoffattyfishaweek.ButtheA.H.A’sexpertpanelwasn’treadytodeclarethattakingomega-3pillswillprotectyourheart.It’sjusttooeasytogetmoreomega-3thanyouneedfrompills,andthepanelwasworriedthatanexcesscouldcauseserioussideeffects,suchasinternalbleeding.
TheU.S.FoodandDrugAdministration,however,allowedmanufacturesofomega-3pillsandfishoilstoadvertisethefat’sbenefits—aslongasthelabeldoesnotsuggesttakingmorethantwogramsperday.
Onethingisclearwhetheryougetyouromega-3sfrompills,oilsorfish:theyarenotcure-alls.Youstillhavetoeatawell-balanceddietthat’slowerintotalfatthanmostAmericanscurrentlyconsume.Otherwise,you’refishingfortrouble.
26.Doctorshavelongbeenpuzzledby.
A.whyredmeatisharmful
B.howbeneficialfishare
C.whatmakesfishhealthful
D.howredmeatisreplaced
正确答案：C
