说明文阅读理解模拟训练 A
Why do mosquitoes buzz (嗡嗡叫) in your ears? They can’t help it. Mosquitoes’ wings make that annoying buzz whenever they fly.
Both male and female mosquitoes buzz, but you probably won’t notice the noise of the males, because they don’t desire your blood. They stay away from your ears, eating nectar (花蜜), while the females come to annoy you.
Scientists have discovered that buzzing is to help mosquitoes find suitable mates.
Since female mosquitoes are larger, they move their wings more slowly. Males can recognize the distinctive pitch (音高) of the females’ buzz. Louis M. Roth, who studied yellow fever mosquitoes for the US Army during World War II, noticed that males ignored females whenever the females were quietly resting, but when the females were flying, and therefore buzzing, the males wanted to mate (交配) with them. The males even reacted to recordings of female mosquitoes.
Scientists discovered what made the sound. It’s not actually caused by the wings flapping. There’s an organ at the base of the wings that makes the sound when the wings move.
It wasn’t until more recently that researchers Gabriella Gibson and Ian Russell discovered that mosquitoes actually change their buzz to “sing” to each other before they mate. When males and females fly nearby, they change the pitch of their buzz to match each other, and if they match well enough, they mate.
As scientists learn more about why mosquitoes buzz, they can possibly keep them from mating. Fewer mosquitoes mean fewer mosquito bites, and fewer diseases being spread. Researcher Lauren Cator suggests that if scientists can make sterile (不生育的) male mosquitoes who “sing” to females just as well as fertile males, the females will choose the sterile males, and won’t produce fertile eggs.
There are also some myths about the mosquitoes you hear buzzing in your ears.
Some people say that mosquitoes that buzz, don’t bite. Indeed, as long as they’re buzzing, they’re flying, so they won’t bite you. But once they land, look out.
1. According to the text, people seldom recognize male mosquitoes when they buzz because ______.
A. their buzz is too low to be noticed
B. they don’t buzz when they bite
C. they avoid humans and feed on nectar
D. they prefer to stay in the dark
2. What did Louis M. Roth discover from his research?
A. Male mosquitoes move their wings slower.
B. Quiet female mosquitoes are more attractive to males.
C. A mosquito’s wing beat is responsible for its buzz.
D. Male mosquitoes are attracted by a female’s buzz.
3. Before mosquitoes mate, they ______.
A. buzz in high pitch to each other B. change and match their buzz
C. dance with each other in mid air
4. Lauren Cator hopes the research on the buzz of mosquitoes can help people ______.
D. fly in opposite directions
A. cure some deadly diseases
B. control the mosquito population
C. tell different mosquito species apart
D. change the way mosquitoes communicate B
The people of Chicago, Illinois, US, can thank three canals every time they drink a glass of clean water today. The building of the Illinois-Michigan Canal, the Chicago Sanitary and Ship Canal and the Cal-Sag Canal all helped the Chicago River start flowing in a different direction in 1892.
Since their construction over a century ago, these waterways have connected Lake Michigan and the Mississippi river network and ensured a regular flow of fresh water to Chicago.
However, some unusual and unfortunate side effects have also been created because of their construction. Asian carp (鲤鱼), also known as silver or flying carp, are threatened in their native habitat in the Chinese Heilongjiang, Yangtze, and Pearl River basins. But they have become increasingly successful at filling the Mississippi river network since first being introduced into Arkansas catfish farms in the 1970s to control algae (水藻). By swimming into the canals and spreading further across the country, there are now major fears that this introduced species may be able to access Lake Michigan and the wider Great Lakes - which store an incredible 21 percent of the entire world’s fresh water.
“The actual impact of Asian carp on the Great Lakes has yet to be explained clearly, and we think this uncertainty is part of the reason why they are such an obvious issue,” says Dr Cory Suski, Associate Professor in the Department of Natural Resources and Environmental Sciences at the University of Illinois. He points out that adult Asian carp are too large to be hunted by anything locally, that they have a “prolific (多产的)” reproduction rate, and they can steal food from the other native species in the rivers. “Could they survive in the Great Lakes or is there not enough food for them?” he asks.
Stopping the fish from spreading has therefore become a key concern for local lawmakers, who have undertaken efforts such as building electric fences (护栏) in the Chicago Sanitary and Ship Canal. However, any big efforts to stop the carp – such as
allowing the Chicago River to once again flow in its original direction – would in turn threaten the security of the city’s water supply, replacing one big problem with another.
5. According to the text, the construction of the three canals ______.
A. changed the direction of the Mississippi river
B. brought fresh water to the people of Chicago
C. lasted for almost a century because of huge cost
D. has been the largest construction project in US history
6. According to the text, Asian carps ______.
A. have nearly become extinct in Chinese rivers
B. have occupied large areas in the Great Lakes
C. were introduced to the US to fight against algae pollution
D. are likely to pollute the fresh water in the Great Lakes
7. What is the major concern of Asian carp in the US?
A. Its large size and fast reproduction rate.
B. The food shortage facing the species.
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