From childhood to old age, we all use language as a means of broadening our knowledge of ourselves and the world about us.When humans first 1__________ , they were like newborn children, unable to use this 2 __________tool.Yet once language developed, the possibilities for human kind future 3__________ and cultural growth increased.

　　Many linguists believe that evolution is 4__________ for our ability to produce and use language.They 5 __________that our highly evolved brain provides us 6__________ an innate language ability not found in lower 7 __________. Proponents of this innateness theory say that our 8__________ for language is inborn, but that language itself develops gradually, 9__________ a function of the growth of the brain during childhood.Therefore there are critical 10__________ times for language development.

　　Current 11 __________of innateness theory are mixed, however, evidence supporting the existence of some innate abilities is undeniable. 12 __________, more and more schools are discovering that foreign languages are best taught in 13 __________grades.Young children often can learn several languages by being 14 __________to them, while adults have a much harder time learning another language once the 15 __________of their first language have become firmly fixed.

　　16 __________some aspects of language are undeniably innate, language does not develop automatically in a vacuum.Children who have been 17__________ from other human beings do not possess language.This demonstrates that 18__________ with other human beings isnecessary for proper language development.Some linguists believe that this is even more basic to human language 19 __________than any innate capacities.These theorists view language as imitative, learned behavior. 20__________ , children learn language from their parents by imitating them.Parents gradually shape their child's language skills by positively reinforcing precise imitations and negatively reinforcing imprecise ones.

　　1.A.generated B.evolved C.born D.originated

　　2.A.valuable B.appropriate C.convenient D.favorite

　　3.A.attainments B.feasibilityC.entertainments D.evolution

　　4.A.essential B.available C.reliable D.responsible

　　5.A.confirm B.inform C.claim D.convince

　　6.A.for B.from C.of D.with

　　7.A.organizations B.organisms C.humans D.children

　　8.A.potential B.performance C.preference D.passion

　　9.A.as B.just as C.like D.unlike

　　10.A.ideological B.biological C.social D.psychological

　　11.A.reviews B.reference C.reaction D.recommendation

　　12.A.In a word B.In a sense C.Indeed D.In other words

　　13.A.various B.different C.the higher D.the lower

　　14.A.revealed B.exposed C.engaged D.involved

　　15.A.regulations B.formations C.rules D.constitutions

　　16.A.Although B.Whether C.Since D.When

　　17.A.distinguished B.different C.protected D.isolated

　　18.A.exposition B.comparison C.contrast D.interaction

　　19.A.acquisition B.appreciation C.requirement D.alternative

　　20.A.As a result B.After all C.In other words D.Above all