Research on animal intelligence always makes us wonder just how smart humans are. (1) the fruit-fly experiments described by Carl Zimmer in the Science Times. Fruit flies who were taught to be smarter than the average fruit fly (2) to live shorter lives. This suggests that (3) bulbs burn longer, that there is a(n) (4) in not being too bright.
Intelligence, it (5) , is a high-priced option. It takes more upkeep, burns more fuel and is slow (6) the starting line because it depends on learning — a(n) (7) process — instead of instinct. Plenty of other species are able to learn, and one of the things they’ve apparently learned is when to (8) .
Is there an adaptive value to (9) intelligence That’s the question behind this new research. Instead of casting a wistful glance (10) at all the species we’ve left in the dust I.Q.-wise, it implicitly asks what the real (11) of our own intelligence might be. This is (12) the mind of every animal we’ve ever met.
Research on animal intelligence also makes us wonder what experiments animals would (13) on humans if they had the chance. Every cat with an owner, (14) , is running a small-scale study in operant conditioning. We believe that (15) animals ran the labs, they would test us to (16) the limits of our patience, our faithfulness, our memory for locations. They would try to decide what intelligence in humans is really (17) , not merely how much of it there is. (18) , they would hope to study a(n) (19) question: Are humans actually aware of the world they live in (20) the results are inconclusive.
9（）
A.invisible
B.limited
C.indefinite
D.different
参考答案：B
解析：
本题各选项的意思分别是：A．invisible(看不见的)；B．limited(有限的)；C．indefinite(不确定的)；D．different(不同的)。本题考查形容词修饰intelligence，由本段第二句话“That’s the question behind this new research.”可知空白所在的问题正是此项研究的课题，而这个研究就是对动物智力的研究。文章开头第一句话就说到对动物智力的研究总是让我们思考人类到底有多聪明，接下来作者用果蝇的例子告诉我们物种越聪明寿命越短，暗示出物种不可能无限的聪明，智力需要有一个适应值 (adaptive value)。第二段又说到智力取决于学习，而大量物种学到的东西之一就是何时停止学习，所以物种的智力应该是有限的，limited符合文意，故选B。