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(diǎn)）.”

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.

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

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

C. Sense of sight. D. Smart brains.

2.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

3.How can we avoid being attacked by mosquitoes 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.

4. 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?

練習(xí)冊系列答案
相關(guān)習(xí)題

科目：高中英語 來源：2016屆河南信陽高級中學(xué)高三上第八次大考英語試卷（解析版） 題型：語法填空

閱讀下面材料，在空白處填入適當(dāng)?shù)膬?nèi)容(不多于3個(gè)單詞)或括號內(nèi)單詞的正確形式按序號填寫到短文后的相應(yīng)位置。

Once, in a lovely garden lived the most beautiful butterfly in the world. She was so pretty, and had won so many beauty competitions1. she had become very proud. One day, a naughty cockroach (蟑螂) got fed up with her showing off, and decided【小題2 】(teach) her a lesson.

She went to see the butterfly, and in front of everyone she told her that she wasn’t really that beautiful, and that the butterfly only won the competitions2. the judges had been paid. In3.(real), the cockroach was the most beautiful.

The butterfly was angry and told the cockroach, “I4.(beat) you in a beauty competition, with whichever judges you choose.” “OK, I accept. See you on Saturday,” answered the cockroach, and left5.waiting for a reply.

That Saturday everyone went to6. beauty competition. The butterfly arrived completely confident of victory until she saw7. the judges were: cockroaches, worms, beetles. All of them8.(prefer) the ugliness and bad smell of the cockroach.

The butterfly was left sobbing and 9.(disappoint), wanting never to enter another beauty competition in her life. Fortunately, the cockroach forgave the butterfly for her pride and they became friends.

查看答案和解析>>

科目：高中英語 來源：2016屆江西豐城中學(xué)高三上學(xué)期第四次月考英語試卷（解析版） 題型：完形填空

完形填空(共20小題；每小題1.5分，滿分30分)閱讀下面短文，從短文后各題所給的四個(gè)選項(xiàng)(A、B、C和D)中，選出可以填入空白處的最佳選項(xiàng)。

I was unbelievably proud of my nine-year-old daughter, Emily. ________ to buy a mountain bike, she’d been saving her pocket money all year, as well as doing small jobs to earn extra money. By Thanksgiving, she had collected only $49. I said, “You ________ have your pick from my bicycle _ ________ .” “Thanks, Daddy. But your bikes are so old.” She was right. All my girls’ bikes were 1950s models, not the kind a kid today would ________ choose.

As Christmas ________ near, Emily and I went bike shopping. As we left one store, she ________ a Salvation Army（基督教慈善組織）volunteer standing next to a big pot. “Can we give something, Daddy?” she asked. “Sorry, em, I’m out of change.” I said.

Throughout December, Emily continued to ________ hard. Then one day, she made a ________ announcement. “You know all the money I’ve been saving?” she said hesitantly. “I’m going to give it to the poor people.” So one cold morning before Christmas, Emily handed her total savings of $58 to a volunteer who was really very ________ .

________ by Emily’s selflessness, I decided to contribute ________ of my old bicycles to a car dealer who was collecting used bikes for poor children. ________ I selected a shiny model from my collection, however, it seemed as if a second bike took on a glow（發(fā)光）.Should I contribute two? No, one would be enough. But I couldn’t ________ the feeling that I should give a second bike. When I later ________ the bikes, the car dealer said, “You’re making two kids very ________ , sir. Here are your tickets. For each bicycle contributed, we’re ________ away one chance to win a girls’ mountain bike.”

Why wasn’t I surprised when that second ticket proved to be the ________ ? I like to think it was God’s way of ________ a little girl for a sacrifice ________ her years---- while giving her dad a lesson in the ________.

1.A. Promised B. Amazed C. Determined D. Organized

2.A. need B. should C. must D. can

3.A. collection B. contribution C. shop D. club

4.A. seldom B. likely C. slightly D. merely

5.A. drew B. became C. went D. pulled

6.A. observed B. sensed C. watched D. noticed

7.A. study B. try C. listen D. work

8.A. disappointing B. surprising C. formal D. public

9.A. agreeable B. hopeful C. thankful D. pitiful

10.A. Moved B. Shocked C. Persuaded D. Demanded

11.A. one B. some C. two D. any

12.A. While B. As C. Because D. Though

13.A. express B. describe C. explain D. shake

14.A. returned B. delivered C. chose D. shared

15.A. sweet B. healthy C. happy D. fair

16.A. putting B. giving C. storing D. signing

17.A. present B. harvest C. winner D. chance

18.A. greeting B. praising C. sheltering D. rewarding

19.A. under B. before C. beyond D. within

20.A. process B. project C. struggle D. communication

查看答案和解析>>

科目：高中英語 來源：2015-2016學(xué)年重慶酉陽二中高二上學(xué)期10月月考英語試卷（解析版） 題型：完形填空

An old man wanted to retire because of his poor health．The was in deciding which son would take his place．As his children gathered to his birthday, the father announced his ．The old man took out two boxes and said to his two sons．“Each of you take one．I want each of you to it with what you believe to be the most thing for our successful business． your choices, I will decide who will take the business,” father saiD． The next days the families and employees could sense the spirit of between the boys.

It was January 1st and the family to celebrate again．“Please with me what’s in your box!” father saiD． The first son said, “It’s outside on the back of truck．The box you gave me was much too ” Father walked to the window and from that distance could see all．With a deep tone of , he asked the other son，“What do you have to give?”The son his father the box．The old man looked inside and with great looked up at his son .“It’s !” father said .“Are you telling me that you have found nothing of value in our business?”

“On the contrary,” he saiD． “I could not place I found most valuable in a box．How does one measure the value of quality and honesty? What size box would the loyalty（忠誠） of our employees and customers? How big of a room would I need for our workers who have from our generous pay and health plan? Finally, father, the most valuable possessions（財(cái)富） I hold are the love of you and mother.”

It was what decision was made that day．There will come a time when each of us will be asked by our father to share what we value most．I hope your box is empty.

1.A． praise B． challenge C． suggestion D． advice

2.A． enjoy B． concern C． celebrate D． honor

3.A． retirement B． experience C． money D． knowledge

4.A． cover B． provide C． combine D． fill

5.A． comfortable B． beautiful C． valuable D． adjustable

6.A． Based on B． Stood for C． Protected from D． Dressed up

7.A． up B． over C． down D． off

8.A． teamwork B． achievement C． competition D． communication9.

9.A． forced B． refused C． adjusted D． gathered

10.A． send B． publish C． share D． write

11.A． big B． small C． light D． large

12.A． happiness B． illness C． sadness D． loneliness

13.A． posted B． packed C． wrapped D． handed

14.A． delight B． shock C． mystery D． devotion

15.A． empty B． wonderful C． terrible D． ugly

16.A． where B． when C． how D． what

17.A． sensed B． measured C． hold D． compared

18.A． benefited B． suffered C． learned D． heard

19.A． severely B． luckily C． sadly D． slightly

20.A． obvious B． nervous C． anxious D． mysterious

查看答案和解析>>

科目：高中英語 來源：2016屆四川廣元市高三上學(xué)期第三次段考英語試卷（解析版） 題型：閱讀理解

Would you want a doctor who got high marks in medical school just for trying hard? Apparently many college students would have no problem with that. They believe students are owed a good grade simply because they put a lot of effort into a class.

The researchers asked more than 800 undergraduates if they agreed or disagreed with some statements. For example: "If I have completed most of the reading for a class, I deserve a B in that course." And: "A professor should not be annoyed with me if I receive an important call during class."

Just 16 percent thought it was OK to take that phone call. But 66 percent agreed that a professor should consider effort and not just the quality of a student's work when deciding grades. And 40 percent thought they should get a B, the second highest mark, just because they did most of the reading for class.

Some experts are not surprised that students often see no difference between effort and results. Social critics like to say that in children's activities these days everyone gets an award just for trying, so no one will feel rejected.

Yet competition to get into the best colleges is fiercer than ever. Students may worry that low grades will keep them out of graduate school or a good job.

And there may be another explanation: pressure from parents to get a good return on the family's investment. These days, college can cost more than a house.

A former teaching assistant recently wrote to the New York Times about his experience with grade expectations. He would try to explain it this way when students asked for a top grade just for studying hard in chemistry class:

What if a baseball player came to spring training and worked harder than all the others, but still could not play well? Would the team accept him anyway, just because he tried so hard?

The students would say no. But most of them would still ask for an A.

1.What does the passage mainly discuss?

A．Whether students deserve high marks just for trying hard.

B．Whether students are allowed to answer calls in class.

C．How students can get a good grade in the course.

D．Why students put a lot of efforts in their studies.

2.According to the research, most of the students _______.

A. thought it was all right to answer the call during class.

B. thought they did most of the work for class and should get a B.

C. objected to deciding grades only by the quality of a student’s work.

D. agreed that they should be given top grades because of their hard work.

3.Which of the following opinions do social critics agree to about children’s activities?

A．Those who are active in the activities can get an award.

B．Only by playing an important role in the activities can you get an award.

C．Whoever takes part in the activities can get an award.

D．An award is prepared for anyone who performs best in the activities.

4.From the sixth paragraph we can learn that _____.

A．it costs much more to build a college than to buy a house.

B．the costs of studying at college are much more than staying at home.

C．the costs of sending a child to college are much more than buying a house.

D．it is difficult for parents to send a child to college.

查看答案和解析>>

科目：高中英語 來源：2016屆北京通州區(qū)潞河中學(xué)高三上學(xué)期期中英語試卷（解析版） 題型：單項(xiàng)填空

There are about 85% of adults _______ the idea of a ban on smoking.

A. welcome B. to welcome

C. welcomed D. welcoming

查看答案和解析>>

科目：高中英語 來源：2016屆山西晉中市四校高三上學(xué)期期中聯(lián)考英語試卷（解析版） 題型：完形填空

閱讀下面短文，掌握其大意，然后從41~60各小題所給的四個(gè)選項(xiàng)A、B、C和D中，選出一個(gè)最佳答案。

One effective way of destroying happiness is to look at something and focus on even the smallest fault. It’s like looking at the tiled(鋪瓦) ceiling and concentrating on the space where one tile is .

Once I heard a bald man said, “whenever I enter a room I see is hair.” Once you’ve what your missing tile is, explore whether acquiring it will make you happy. Then do one of the three things: Get it, replace it with a different , or forget about it and the tiles in your life that are not missing.

We all know people who have a relatively life, yet are essentially unhappy while people who have suffered a great deal but remain happy.

The first is gratitude. All happy people are . Ungrateful people cannot be happy. We tend to think that being unhappy leads people to , but it’s truer to say that complaining leads people to becoming unhappy.

The second secret is that happiness is a byproduct of something else. The most obvious________are those pursuits that give our lives purpose—anything studying insects to playing baseball. The more passions we have, the more happiness we are to experience.

Finally, the belief that something permanent goes beyond us and that our ________ has some larger meaning can help us to feel happier. We ________ a spiritual faith, or a philosophy; it should this truth: if you choose to find the ________ in every situation, you will be blessed, and if you choose to find the awful, you will be cursed. As with happiness itself, this is ________ your decision to make.

1.A. different B. missing C. short D. broken

2.A. nothing B. none C. all D. anything

3.A. determined B. predicted C. assumed D. imagined

4.A. completely B. naturally C. hopefully D. really

5.A. tile B. brick C. ceiling D. house

6.A. look on B. focus on C. count on D. rely on

7.A. peaceful B. difficult C. easy D. ordinary

8.A. certainly B. merely C. hardly D. generally

9.A. secret B. factor C. rule D. key

10.A. wealthy B. grateful C. proud D. generous

11.A. upset B. quarrel C. complain D. depress

12.A. admitting B. assuming C. proving D. realizing

13.A. sources B. results C. answers D. goals

14.A. among B. from C. through D. for

15.A. probable B. possible C. likely D. capable

16.A. value B. destination C. survival D. existence

17.A. need B. lack C. demand D. expect

18.A. involve B. include C. absorb D. mean

19.A. worst B. best C. positive D. negative

20.A. absolutely B. totally C. exactly D. largely

查看答案和解析>>

科目：高中英語 來源：2016屆浙江寧波效實(shí)中學(xué)高三上期中英語試卷（解析版） 題型：單項(xiàng)填空

Sara, my colleague, has been ______ the run all week preparing for her son’s wedding.

A. in B. to C. on D. at

查看答案和解析>>

科目：高中英語 來源：2015-2016學(xué)年江西豐城中學(xué)高一上學(xué)期期中英語試卷（解析版） 題型：閱讀理解

When my sister Gina was born, she had a problem with her heart. Her heart was pretty bad in the beginning and she stayed in the hospital for a month. The first few years were very difficult because she was very sick. She had five operations before she was three years old. She had trouble walking, playing with other children, and going to school.

Although Gina couldn’t laugh and talk, we all knew that she just needed love and care. Our parents wanted to take Gina to a special place in Florida. There she could swim with dolphins. Gina was afraid of swimming with them because she had never been around dolphins before. We had also never traveled that far as a family. When we got to Florida, we saw where the dolphins lived. It was a place where kids with special needs like Gina could come and spend time. I thought it was going to be a vacation, but it wasn’t. Gina had to work hard every day for a week.

The trip was amazing. Gina laughed and clapped when she saw the dolphin. The dolphin splashed（濺起水花） when it saw Gina. They swam together all day. Gina was able to move her body more than she normally did at home. Mom and Dad were proud of Gina. I was , too.

1.We know from the text that Gina_________.

A. experienced five operations in a month

B. got along well with other children

C. stayed in the hospital before three

D. was born with a heart disease

2.The author’s family went to Florida to _______.

A. treat Gina for her illness.

B. have a family trip

C. see the dolphins

D. learn to swim

3.How did Gina feel about swimming with dolphins at first?

A. Excited B. Frightened C. Angry D. Proud

4.The text is written to tell us that ________.

A. Learning to walk is hard work

B. dolphins can treat many illnesses

C. families should travel together often

D. help sometimes comes in unusual forms

查看答案和解析>>

同步練習(xí)冊答案