{{B}}pAssAgE Four{{/B}}

whEn sCiEntists ArE trying to unDErstAnD A pArtiCulAr sEt oF phEnomEnA, thEy oFtEn mAkE usE oF A "moDEl."A、moDEl, in thE sCiEntists’ sEnsE, is A kinD oF AnAlogy or mEntAl imAgE oF thE phEnomEnA in tErms oF somEthing wE ArE FAmiliAr with. onE ExAmplE is thE wAvE moDEl oF light. wE CAnnot sEE light As iF it wErE mADE up oF wAvEs BECAusE ExpErimEnts on light inDiCAtE thAt it BEhAvEs in mAny rEspECts As wAtEr wAvEs Do. thE purposE oF A moDEl is to givE us A mEntAl or visuAl piCturE -- somEthing to holD onto -- whEn wE CAnnot sEE whAt is ACtuAlly hAppEning. moDEls oFtEn givE us A DEEpEr unDErstAnDing: thE AnAlogy to A known systEm (For instAnCE, wAtEr wAvEs in thE ABovE ExAmplE) CAn suggEst nEw ExpErimEnts to pErForm AnD CAn proviDE iDEAs ABout whAt othEr rElAtED phEnomEnA might oCCur.

AnothEr ExAmplE oF A sCiEntiFiC moDEl woulD BE ______.A．A mAp
B．A pApEr AirplAnE
C．An Atom
D．A light BulB