Read the following passage and mark the letter A, B, C or B on your answer sheet to indicate the correct answer to each of the questions from 30 to 37.
Many ants forage across the countryside in large numbers and undertake mass migrations; these activities proceed because one ant lays a trail on the ground for the others to follow. As a worker ant returns home after finding a source of food, it marks the route Line by intermittently touching its stinger to the ground and depositing a tiny amount of trail pheromone – a mixture of chemicals that delivers diverse messages as the context changes.
These trails incorporate no directional information and may be followed by other ants in either direction. Unlike some other messages, such as the one arising from a dead ant, a food trail has to be kept secret from members of other species. It is not surprising then that ant species use a wide variety of compounds as trail pheromones. Ants can be extremely sensitive to these signals. Investigators working with the trail pheromone of the leafcutter ant Atta texana calculated that one milligram of this substance would suffice to lead a column of ants three times around Earth. The vapor of the evaporating pheromone over the trail guides an ant along the way, and the ant detects this signal with receptors in its antennae. A trail pheromone will evaporate to furnish the highest concentration of vapor right over the trail, in what is called a vapor space. In following the trail, the ant moves to the right and left, oscillating from side to side across the line of the trail itself, bringing first one and then the other antenna into the vapor space. As the ant moves to the right, its left antenna arrives in the vapor space. The signal it receives causes it to swing to the left, and the ant then pursues this new course until its right antenna reaches the vapor space. It then swings back to the right, and so weaves back and forth down the trail.
The author mentions the trail pheromone of the leafcutter ant in line 11 to point out
A. how little pheromone is needed to mark a trail
B. the different types of pheromones ants can produce
C. a type of ant that is common in many parts of the world
D. that certain ants can produce up to one milligram of pheromone
Giải bởi qa.haylamdo.com
Đáp án A
Tác giả đề cập đến dấu vết pheromone của kiến cắn lá ở dòng 11 để chỉ ra
A. cần rất ít Pheromone để đánh dấu một dấu vết
B. các loại pheromones khác nhau mà kiến có thể sản sinh
C. một loại kiến phổ biến ở nhiều nơi trên thế giới
D. Một số kiến có thể sản sinh đến một miligam pheromone
Dẫn chứng: Investigators working with the trail pheromone of the leafcutter ant Atta texana calculated that one milligram of this substance would suffice to lead a column of ants three times around Earth.
Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions.
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Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions.
_________ the flight delay, they didn’t attend the conference.
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Mark the letter A, B, C or D on your answer sheet to indicate the most suitable response to complete each of the following exchanges.
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Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions.
In the past, the trip _________ very rough and often dangerous, but things _________ a great deal in the last hundred and fifty years
Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions.
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Mark the letter A, B, C or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions.
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Mark the letter A, B, C or D on your answer sheet to indicate the most suitable response to complete each of the following exchanges.
The telephone rings but it is someone who has a wrong number, you put the phone down after saying:
Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions.
After more than a decade of Doi Moi or economic _________ , the Vietnamese Communist government has achieved diplomatic and economic links with numerous foreign partners.
Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions.
A _________ is a landscape or region that receives very little precipitation.
Mark the letter A, B, C or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions.
“Would you like something to drink?” he asked.
Mark the letter A. B, C or D on your answer sheet to indicate the word that differs from the other three in the position of primary stress in each of the following questions.
Mark the letter A, B, C or D on your answer sheet to indicate the word whose underlined part differs from the other three III pronunciation In each of the following questions.
