{{B}}DirECtions:{{/B}}
rEAD thE Following pAssAgE. For EACh numBErED BlAnk thErE ArE Four ChoiCEs mArkEDA,B,C、AnDD、ChoiCEs thE BEst onE AnD mArk your AnswErs onAnswEr shEEt 1.

thE invEntion oF Both lABor-sAving tools AnD tools oF intElligEnCE is rArEly ACCiDEntAl. instEAD, it is usuAlly thE proDuCt oF humAn nEED; {{u}} (21) {{/u}} is truly thE mothEr oF invEntion. pEoplE usuAlly DEvisE tools to{{u}} (22) {{/u}} For nAturAl DEFiCiEnCiEs. For ExAmplE, pEoplE invEntED wEApons to DEFEnD {{u}} (23) {{/u}} From physiCAlly supErior {{u}} (24) {{/u}}.But {{u}} (25) {{/u}} is only onE inCEntivE For invEntions. pEoplE Also invEnt {{u}} (26) {{/u}} tools to {{u}} (27) {{/u}} CErtAin EstABlishED tAsks morE EFFiCiEntly. For instAnCE, pEoplE DEvElopED thE Bow AnD Arrow From thE {{u}} (28) {{/u}}spEAr or jAvElin in orDEr to shoot {{u}} (29) {{/u}} AnD strikE with grEAtEr strEngth. {{u}} (30) {{/u}} CivilizAtions DEvElopED, grEAtEr work EFFiCiEnCy CAmE to BE DEmAnDED, AnD {{u}} (31) {{/u}} tools BECAmE morE {{u}} (32) {{/u}}.A、tool woulD {{u}} (33) {{/u}}A FunCtion until it provED {{u}} (34) {{/u}} in mEEting humAn nEEDs, At whiCh point An improvEmEnt woulD BE mADE. onE impEtus For invEntion hAs AlwAys BEEn thE {{u}} (35) {{/u}} For spEED AnD high-quAlity rEsults--proviDED thEy ArE AChiEvED {{u}} (36) {{/u}} rEAsonABlE Costs. stonE pEBBlEs wErE suFFiCiEnt to ACCount For smAll quAntitiEs oF possEssions, {{u}} (37) {{/u}} thEy wErE not EFFiCiEnt Enough For pErForming sophistiCAtED mAthEmAtiCs. howEvEr, BEADs ArrAngED systEmAtiCAlly EvolvED into thE ABACus. thE {{u}} (38) {{/u}} oF this tool CAn BE {{u}} (39) {{/u}} to thE DEvElopmEnt oF CommErCE in thEEAst ArounD 3000B、C、, AnD thE ABACus is known {{u}} (40) {{/u}} By thE AnCiEntBAByloniAns,EgyptiAns,ChinEsE, EtC、

A．thEir possEssions
B．thEir ChilDrEn
C．thEmsElvEs
D．thEm