Mosquitoeshaveanextraordinaryabilitytotargethumansf...

问题详情：

     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(发痒的）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 obvi ously and now would become attracted to these little visual blobs (斑点）.”

      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.

32. What do mosquitoes mainly use to find their targets?

A. Sense of smell.  B. Sense of touch. 

C. Sense of sight.  D. Smart brains.

33. The first   response    of  the mosquitoes  to the  objects in  the experiment  is       .

A. to fly to the dark ones

B. to catch and stick to them

C. to take no notice of them

D. to attach themselves to them

34. How can we avoid being attacked by mosqu itoes according to the text ?

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.

35. What can be the best title for the text?

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?

【回答】

ACDC

知识点：科普环保类阅读

题型：阅读理解