Almost everyone wants to get smarter. We struggle to improve our 16_ , intelligence and at

Almost everyone wants to get smarter. We struggle to improve our 16_ , intelligence and attention. We drink cup after cup of coffee to help us  17_  the day.
 18     , a new study published in Current Directions in Psychological Science warns that there are 19     to how smart humans can get.
Each of our body parts develops in a certain way for a reason.  20  _, we are not 3 meters tall  21 _ most people’s hearts are not strong enough to send  22 _  up that high. Scientists say that our thinking ability works in the same way. A baby’s brain size is limited by a series of     23  , such as the size of the mother’s pelvis (骨盆). If our brains developed to be bigger, there could be more  24  during childbirth.
The study of Jews, who have an average IQ much _ 25_  than other Europeans, showed they were more  _26_  to develop diseases of the  _27_  system. This might be because of their increased brainpower.
If intelligence cannot be improved, can we at least get better at _ 28 _ ? Not really, say scientists. They studied  _29_  like caffeine (咖啡因)that improve attention. They found the drugs only helped people with serious  30 _ problems. For those who did not have trouble paying attention, the drugs could have the  31 _ effect. Scientists say that this suggests there is a(n)  32 limit to how much people can or should concentrate.
Our memory is also a “double-edged sword”. People with extremely good memories could  33     having a difficult life because they cannot  _34 bad things that happen to them.
Thomas Hills, one of the authors of the paper, said that   35  all the problems in trying to get smarter, it’s unlikely that there will ever be a “super mind”.
【小题1】A．memoryB．characterC．.abilityD．emotion【小题2】A．go throughB．get throughC．put through D．carry through【小题3】A．Though B．ThereforeC．MeanwhileD．However【小题4】A．standardsB．measuresC．rangesD．limits【小题5】A．For exampleB．In additionC．At firstD．Above all【小题6】A．untilB．beforeC．becauseD．so that【小题7】A. blood      B information        C. breath            D. strength
【小题8】A．reasonsB．factorsC．aspectsD．effects【小题9】A．chancesB．livesC．choicesD．deaths【小题10】A．smarterB．betterC．higherD．lower【小题11】A．likelyB．possibleC．probableD．sure【小题12】A．nervousB．bodilyC．personalD．physical【小题13】A．exercisingB．concentrating C．memorizingD．thinking【小题14】A．poisonsB．drinks C．plants D．drugs【小题15】A．healthB．familyC．attentionD．living【小题16】A．sameB．differentC．oppositeD．similar【小题17】A．lowerB．smallerC．higherD．upper【小题18】A．end up B．make upC．start upD．e up【小题19】A．rememberB．forgetC．performD．share【小题20】A．supposingB．consideringC．concerningD．regardingA