某缺铁性贫血患者服用铁剂治疗后出现黑便，护士应向其解释黑便发生的原因是
Passage1
Questions1to5arebasedonthefollowingpassage:
DoyouwanttosaywhatyouthinkinalettertothePresidentoftheUnitedStates?You’llgetareplyfromhim—writteninink,nottyped—afteronlyafewdays.
ThePresidentgetsabout4,000letterseveryweek.HeanswerseveryonewhowritestohimonspecialWhitesHousepaper.Buthedoesn’tneedalotoftimeforit.Infact,heonlygives20minutesaweektolookathispersonalcorrespondence.Hehasthemostmodernsecretaryintheworldtohelphim.
It’scomputer,worth￡800，000，whichhasitsownroomsonthefirstflooroftheWhiteHouse.IthasabankofelectronicpenswhichwritelikethePresidentwrites,inhisfavoritelightblueink.EachletterthePresidentreceivesgetsanumber,accordingtothetypeofansweritneeds.Thepensthenwritethecorrectreplyforit,accordingtothenumber.Eachlettertakeslessthanasecondtowrite.AWhiteHouseofficialsaid,“It’snotimportantthatletterscomefromacomputer.EachlettersayswhatthePresidentwantstosay.”
1.forareplyfromthePresident.
A.YouhavetowaitalongtimeB.Youonlyhavetowaitseveraldays
C.YouhavetowaitatleastonemonthD.Youonlyhavetowaitafewweeks
2.ThereplyfromthePresident.
A.isalwaysprintedB.isalwaystyped
C.isalwayswrittenininkD.isalwayswrittenbyhimself
3.Ittakesthecomputertowritetenletters.
A.nomorethantensecondsB.alittlemorethantenseconds
C.lessthantensecondsD.atleastonesecond
4.Thecomputercanbedescribedas.
A.expensivebutefficientB.possessingabeautifulhandwriting
C.heavyandinefficientD.thePresident’smostreliablesecretary
5.Itcanbeinferredfromthepassagethat.
A.thePresidentneverreadsanyletterswrittentohimbyordinarypeople
B.thePresidenthiresaveryefficientsecretarytodealwithhiscorrespondence
C.thePresidentdoesnotreallycareaboutthelettershereceiveseveryweek
D.thePresidentisassuredthatthecomputerexpresshisviewsintheletters