a microscope is a useful instrument for observing 阅读理解答案

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1、Amicroscopeisausefulinstrumentforobserving阅读理解答案　　Amicroscopeisausefulinstrumentforobservingsmallobjects.Byproducingabiggerimage,themicroscoperevealsdetailsthatareundetectabletothenakedeye(裸眼).　　Beforeusingthemicroscope,pleasereadtheinstructionsbelow.　　CAUTION:Microscopesarebothdelicateandexpens

2、iveandmustbehandledwithcare.　　1.Alwayscarrythemicroscopewithtwohands—onesupportingthebaseandtheotheronthearm.　　2.Avoidstretchingthewireofthelampacrossawalkway.　　3.Keepthestagecleanandalwaysuseaglassslideforspecimens(样本).　　4.Toavoidcrushingtheglassslidewhenfocusing,beginwiththelensclosetothespeci

3、menandgraduallybackofftofocus.　　5.Keepthemicroscopecoveredtopreventthedustwhileitisbeingstored.　　HOWTOUSETHEMICROSCOPE:　　1.Plug(接通电源)inthelamp.　　2.Placeasampleofwhatyouwishtoobserveonaslide.　　3.Adjustthemirrorsoitreflectslightfromtheroomupintotheobjectivelens.Whenthemirroriscorrectlyadjusted,aco

4、mpletecircleoflightwillappearwhenyoulookthroughtheeyepiece.　　4.Placeyourslidewiththespecimendirectlyoverthecenteroftheglasscircleonthestage.Ifitisawetslide,besurethebottomoftheslideisdry.　　5.WiththeLOWPOWERobjectivelensplacedovertheslide,usethecoarsefocusknobtolowerthelenstothelowestpoint.　　6.Lo

5、okthroughtheeyepiecewithoneeyewhileclosingtheothereye.Slowlyraisethelensuntilthefocusisrelativelyclear.　　7.Usethefinefocusknobtofine-tune(微调)thefocus.　　8.Withoutchangingthefocusknobs,switchtotheHIGHPOWERobjectivelens.OnceyouhaveswitchedtoHIGHPOWER,useonlythefinefocusknobtomaketheimagesharper.　　5

6、0.Whichofthefollowingisthecorrectwaytouseamicroscopeaccordingtothetext　　A.Useonehandtocarrythemicroscope　　B.Placeasampledirectlyonthecleanstage　　C.Whenstored,themicroscopeshouldbeadjusted.　　D.Lookthroughtheeyepiecewithoneeye.　　51.Ifyouwanttoobserveathinpieceofhair,whichofthefollowingshouldyoudof

7、irst　　A.SwitchtoobjectivelensB.Adjustthemirror　　C.LookthroughtheeyeD.Placethehaironaglassslide　　52.Accordingtothetext,youcouldseeacompletecircleoflight_____.　　A.aftercorrectlyadjustingthemirror　　B.whilelookingatthespecimenon