Read the passage and choose the best option to complete each blank.
Any change in one part of an ecosystem can cause changes in other parts. Droughts, storms and fires can change ecosystems. Some changes ____(46)___ ecosystems. If there is too little rainfall, plants will not have enough water to live. If a kind of plant dies off, the animals____(47)___feed on it may also die or move away. Some changes are good for ecosystems. Some pine forests need fires for the pine trees to reproduce. The seeds are sealed inside pinecones. Heat from a forest fire melts the seal and lets the seeds ____(48)___. Polluting the air, soil, and water can harm ecosystems. Building dams on rivers for electric power and irrigation can harm ecosystems ____(49)___ the rivers. Bulldozing wetlands and cutting down forests destroy ecosystems. Ecologists are working with companies and governments to find better ways of ___(50)____ fish, cutting down trees, and building dams. They are looking for ways to get food, lumber, and other products for people without causing harm to ecosystems
Điền ô số 46
A. harms
B. harmful
C. harmless
D. harm
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Đáp án D
Ở đây ta cần một động từ
Động từ harm: gây hại, làm hại
It was found that he lacked the ________ to pursue a difficult task to the very end.
Mark the letter A, B, C or D on your answer sheet to indicate the word or phrase that is closest in meaning to the underlined part in each of the following questions.
His new yacht is certainly an ostentatious display of his wealth
Could you stand_________ for me and teach my English class tomorrow morning, John?
Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning
Had she read the reference books, she would have been able to finish the test.
Mark the letter A, B, C, or D on you answer sheet to indicate the sentence that best combines each pair of sentences in the following questions.
We cut down many forests. The Earth becomes hot
Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning
It started to rain at 2 o’clock and it is still raining
Choose the word whose underlined part is pronounced differently from others
Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning
“I will pay back the money, Gloria.” Said Ivan
It was ____ easy for him to learn baseball because he had been a cricket player.
Do you know that beautiful lady over there?” - “Yes, that’s Victoria. She’s ____ in her group.”
Christine ...... have arrived by now, she _______ have missed the bus.
Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions
He takes four paracetamol everyday, not knowing that will seriously damage his liver
Read the following passage and mark the letter A, B, C ,or D on your answer sheet to indicate the correct answer for each of the questions.
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 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.
According to the passage, the highest amount of pheromone vapor is found
