Teacher: Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.
Teacher: Now, understand the problem? If you are still confused, see the following example:
In 1582 the united provinces invited francis, duke of anjou to lead them; but after a failed attempt to take antwerp in 1583, the duke left the netherlands again. after the assassination of william of orange (10 july 1584), both henry iii of france and elizabeth i of england declined the offer of sovereignty. however, the latter agreed to turn the united provinces into a protectorate of england (treaty of nonsuch, 1585), and sent the earl of leicester as governor-general. this was unsuccessful and in 1588 the provinces became a confederacy. the union of utrecht is regarded as the foundation of the republic of the seven united provinces, which was not recognized by the spanish empire until the peace of westphalia in 1648.
Solution: In what year did francis, duke of anjou leave the netherlands?
Reason: The generated question is perfect. Because the question is based on second sentence of the input passage and its answer is 1583.

Now, solve this instance: 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 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 ." 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.
Student:
What do mosquitoes mainly use to find their targets?