Question

19．Mosquitoes have an extraordinary ability to target humans far away and fly straight to their unprotected skin．Regrettably，mosquitoes can do more than cause an itchy（發(fā)癢的）wound．Some mosquitoes spread several serious diseases，including Dengue，yellow fever and malaria．
Over one million people worldwide die from these diseases each year．New research now   shows how mosquitoes choose who to bite．
Mosquitoes need blood to survive．They are attracted to human skin and breath．They smell the carbon dioxide gas，which all mammals breathe out．This gas is the main way for mosquitoes to know that a warm-blooded creature is nearby．
But mosquitoes also use their eyes and sense of touch．Michael Dickinson is a professor at the California Institute of Technology．His research shows how these small insects，with even smaller brains，use three senses to find a blood meal．
Michael Dickinson's team used plumes-a material that rises into the air of carbon dioxide gas into a wind tunnel．They then used cameras to record the mosquitoes．The insects followed the plume．
Then，the scientists placed dark objects on the lighter colored floor and walls of the tunnel．Mr．Dickinson said，at first，the mosquitoes showed no interest in the objects at all．"What was quite striking and quite surprising is that the mosquitoes fly back and forth for hours．These are hungry females and they completely ignore the objects on the floor and wall of the tunnel．But the moment they get a hit of CO2，they change their behavior quite obviously and now would become attracted to these little visual blobs （斑點）．"
This suggested to the researchers that a mosquito's sense of smell is more important in the search for food．Once mosquitoes catch a smell of a human or animal，they also follow visual signals．
12．What do mosquitoes mainly use to find their targets？A
A．Sense of smell              
B．Sense of touch
C．Sense of sight              
D．Smart brains
13．The first response of the mosquitoes to the objects in the experiment isC．
A．to fly to the dark ones         
B．to cat ch and stick to them
C．to take no notice of them       
D．to attach themselves to them
14．How can we avoid being attacked by mosquitoes according to the text？D
A．Don't let them see us．
B．Use dark objects to stop them．
C．Make them fly back and forth for hours．
D．Attract them to objects full of carbon dioxide gas．
15．What can be the best title for the text？C
A．How Do Mosquitoes Survive？
B．Why Do Mosquitoes Need Blood？
C．How Do Mosquitoes Choose to Bite You？
D．Why Do Mosquitoes Attack the Human Being？

Answer 1

分析 本文解釋了蚊子叮人的依據(jù)，通過實驗發(fā)現(xiàn)蚊子是依靠二氧化碳來追蹤叮咬目標．

解答 12．A細節(jié)理解題．根據(jù)句子This gas is the main way for mosquitoes to know that a warm-blooded creature is nearby．可以得出蚊子依靠嗅覺叮人，所以選A．
13．C 細節(jié)理解題． Mr．Dickinson said，at first，the mosquitoes showed no interest in the objects at all．狄金森先生說，起初，蚊子對對象根本不感興趣．stick to 粘著；take no notice of 不注意；attach ones to依附著．所以答案為C．
14．D 推理判斷題．But the moment they get a hit of CO2，they change their behavior quite obviously and now would become attracted to these little visual blobs 但是，當他們受到二氧化碳的影響，他們改變他們的行為非常明顯，現(xiàn)在會吸引這些小視覺斑點．可以推斷出蚊子對二氧化碳敏感可以用二氧化碳誘騙蚊子，所以答案 選D．
15．C主旨大意題．New research now   shows how mosquitoes choose who to bite．新的研究表明蚊子是如何選擇咬人的．得出本文的主旨，所以答案選C．

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