12．There are two factors which determine an individual's intelligence．The first is the sort of brain he is born with．Human brains differ considerably，some being more capable than others．But no matter how good a brain he has to begin with，an individual will have a low order of intelligence unless he has opportunities to learn．So the second factor is what happens to the individual-the sort of environment in which he is reared．If an individual is handicapped envionmentally，it is likely that his brain will fail to develop and he will never attain the level of intelligence of which he is capable．
The importance of environment in determining an individual's intellingence can be demonstrated by the case history of the identical twins，Peter and Mark．Being identical，the twins had identical brains at birth，and their growth processes were the same．When the twins were three months old，their parents died，and they were placed in separate foster homes．Peter was reared by parents of low intelligence in an isolated community with poor educational opportunities．Mark was reared in the home of well-to-do parents who had been to college．He was read to as a child，sent to good schools，and given every opportunity to be stimulated intellectually．This enviromental difference continued until the twins were in their late teens，when they were given tesets to measure their intelligence．Mark's I．Q．was 125，twenty-five points higher than the average and fully forty points higher than his identical brother．Given equal opportunities，the twins，having identical brains，would have tested at roughly the same level．
28．This selection can best be titledB．
A．Measuring Your Intelligence
B．Intelligence and Environment
C．The Case of Peter and Mark
D．How the brain Influences Intelligence
29．According to the passage，the average I．Q．isB．
A.85 B.100 C.110 D.125
30．The case history of the twins appears to support the conclusion thatC．
A．individual with identical brains seldom test at same level
B．a(chǎn)n individual's intelligence is determined only by his enviroment
C．lack of opportunity blocks the growth of intelligence
D．changes of enviroment produce changes in the structure of the brain．
分析 本文講述了關(guān)于智力發(fā)展的因素．第一個是先天性的因素，第二個也是更重要的一個因素就是環(huán)境因素．文章根據(jù)雙胞胎的案例，說明了缺乏受教育的機會會阻礙了智力的增長．可見環(huán)境對于智力發(fā)展的影響很大．
解答 28-30．BBC
28．B 考查文章主旨．根據(jù)"The importance of environment in determining an individual's intellingence"可知，本文要講述的是環(huán)境在決定個人的智力方面的重要性．故選B．
29．B 考查細節(jié)理解．根據(jù)"Mark's I．Q．was 125，twenty-five points higher than the average"可知，對于125的IQ成績來說，是高于平均IQ25分，可計算出平均IQ應(yīng)當是100．故選B．
30．C 考查推理判斷．根據(jù)雙胞胎的案例可知，缺乏受教育的機會會阻礙了智力的增長．故選C．
點評 閱讀理解考察學(xué)生的細節(jié)理解和推理判斷能力，做細節(jié)理解題時一定要找到文章中的原句，和題干進行比較，再做出正確的選擇．在做推理判斷題不要以個人的主觀想象代替文章的事實，要根據(jù)文章事實進行合乎邏輯的推理判斷．
