Câu hỏi:
17/06/2026 461Read the passage and choose the best answer.
A pilot cannot fly by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300,000 kilometers in one second. A radar set sends out a short burst of radio waves. Then it receives the echoes produced when the waves bounce off objects. By determining the time it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word “radar”, in fact, gets its name from the term “radio detection and ranging”. “Ranging” is the term for detection of the distance between an object and the radar set. Besides being of critical importance to pilots, radar is essential for air traffic control, tracking ships at sea, and for tracking weather systems and storms.
Which of the following words best describes the tone of this passage?
A. argumentative
B. explanatory
C. humorous
D. imaginative
Trả lời:
Giải bởi Vietjack
Đáp án B
Bài viết cung cấp thông tin chi tiết và logic về cách hoạt động của radar, vai trò của nó và ý nghĩa của từ "radar" => Giọng điệu của đoạn văn là giải thích (explanatory)
Theo thông tin bài văn cung cấp, ta thấy:
- "A pilot cannot fly by sight alone..."
- "The basic principle of radar is exemplified by what happens when one shouts in a cave..."
- "By determining the time it takes for the echoes to return..."
Dịch nghĩa: “Một phi công không thể chỉ bay dựa vào tầm nhìn. Trong nhiều điều kiện, chẳng hạn như bay vào ban đêm và hạ cánh trong sương mù dày đặc, phi công phải sử dụng radar, một phương pháp điều hướng thay thế. Vì mắt người không giỏi xác định tốc độ của các vật thể đang tiến gần, radar có thể hiển thị cho phi công tốc độ di chuyển của các máy bay gần đó.
Nguyên lý cơ bản của radar được minh họa bằng hiện tượng xảy ra khi một người hét lên trong hang động. Tiếng vọng của âm thanh dội lại từ các bức tường giúp người đó xác định kích thước của hang. Tuy nhiên, với radar, sóng dội lại là sóng vô tuyến thay vì sóng âm thanh. Sóng vô tuyến di chuyển với tốc độ ánh sáng, khoảng 300.000 km mỗi giây.
Một bộ radar phát ra một loạt sóng vô tuyến ngắn. Sau đó, nó nhận các tín hiệu vọng lại khi sóng dội vào các vật thể. Bằng cách xác định thời gian các tín hiệu vọng lại trở về bộ radar, một kỹ thuật viên được đào tạo có thể tính toán khoảng cách giữa radar và các vật thể khác.
Thực tế, từ “radar” lấy tên từ cụm từ “radio detection and ranging” (phát hiện và đo khoảng cách bằng sóng vô tuyến). “Ranging” là thuật ngữ chỉ việc xác định khoảng cách giữa một vật thể và bộ radar. Ngoài vai trò cực kỳ quan trọng đối với phi công, radar còn rất cần thiết trong kiểm soát không lưu, theo dõi tàu biển, và theo dõi các hệ thống thời tiết và bão.”
CÂU HỎI HOT CÙNG CHỦ ĐỀ
Câu 1:
Read the passage and choose the best answer.
A pilot cannot fly by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300,000 kilometers in one second. A radar set sends out a short burst of radio waves. Then it receives the echoes produced when the waves bounce off objects. By determining the time it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word “radar”, in fact, gets its name from the term “radio detection and ranging”. “Ranging” is the term for detection of the distance between an object and the radar set. Besides being of critical importance to pilots, radar is essential for air traffic control, tracking ships at sea, and for tracking weather systems and storms.
According to the passage, what can radar detect besides location of objects?
Câu 2:
Read the passage and choose the best answer.
A pilot cannot fly by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300,000 kilometers in one second. A radar set sends out a short burst of radio waves. Then it receives the echoes produced when the waves bounce off objects. By determining the time it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word “radar”, in fact, gets its name from the term “radio detection and ranging”. “Ranging” is the term for detection of the distance between an object and the radar set. Besides being of critical importance to pilots, radar is essential for air traffic control, tracking ships at sea, and for tracking weather systems and storms.
What might be inferred about radar?
Câu 4:
A thirteen-year-old does not spend as much money as his parents suspect - at least not (1) ………….the findings of recent survey, Money and Change. The survey (2) ……….. three hundred teenagers, 13-17 years old from (3) …………. Britain.
By the time they (4) ………… their teens, most children see their weekly allowance rise dramatically to an amazing national average of $5.14. Two thirds think they get (5) …………. money but most expect to have to do something to get it.
Although they have more cash, worry about debt is (6) ………….. among teenagers. Therefore, the majority of children make an effort to save for the future.
Greater access to cash (7) ……………. teenagers does not, however, mean that they are more irresponsible as a result. The economic recession seems to have encouraged cautious attitudes to money, even in the case of children at these ages. Instead of wasting what pocket (8) …………… they have on sweets or magazines, the teenagers who took (9) …………. in the survey seem to respond to the situation by saving more than half (10) …………. their cash.
Điền vào số 4
Câu 5:
Read the passage and choose the best answer.
A pilot cannot fly by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300,000 kilometers in one second. A radar set sends out a short burst of radio waves. Then it receives the echoes produced when the waves bounce off objects. By determining the time it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word “radar”, in fact, gets its name from the term “radio detection and ranging”. “Ranging” is the term for detection of the distance between an object and the radar set. Besides being of critical importance to pilots, radar is essential for air traffic control, tracking ships at sea, and for tracking weather systems and storms.
According to the passage, the distance between a radar set and an object can be determined by _______.
Câu 6:
Read the passage, then choose the best answer by circling the letter A, B, C or D ( 15p ):
In the very distant geological past, all animals were aquatic. The very first vertebrates or animals with backbones, of which we have any fossil record, lived in water. These vertebrates, the fish, were adapted to underwater living. Their streamlined bodies were covered with scales to reduce surface friction: they had muscular tails so that they could swim swiftly in such a dense medium as water; and they were endowed with gills for breathing underwater.
Descendants of fish-type ancestors crossed the seashore barrier and accommodated themselves to life on land.
As amphibians, they possessed limbs instead of fins and lungs instead of gills. But they never became completely free of the bonds that tied them to the water; even today many amphibians return to the water to lay their eggs.
Millions of years after the first clumsy amphibians crawled over the land, newer types of land dwellers appeared, these animals give rise to the present-day reptiles and mammals. They were completely converted for land dwelling, with bodies and biological activities far different from those of fish. With these special adaptations, mammals have been able to colonize the woods and meadows, the deserts and high mountains, often far removed from the sea.
Of the animals with backbones, the first to appear were………………
Câu 7:
Read the passage and choose the best answer.
A pilot cannot fly by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300,000 kilometers in one second. A radar set sends out a short burst of radio waves. Then it receives the echoes produced when the waves bounce off objects. By determining the time it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word “radar”, in fact, gets its name from the term “radio detection and ranging”. “Ranging” is the term for detection of the distance between an object and the radar set. Besides being of critical importance to pilots, radar is essential for air traffic control, tracking ships at sea, and for tracking weather systems and storms.
What is the main topic of this passage?
Câu 8:
Read the passage and choose the best answer.
A pilot cannot fly by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300,000 kilometers in one second. A radar set sends out a short burst of radio waves. Then it receives the echoes produced when the waves bounce off objects. By determining the time it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word “radar”, in fact, gets its name from the term “radio detection and ranging”. “Ranging” is the term for detection of the distance between an object and the radar set. Besides being of critical importance to pilots, radar is essential for air traffic control, tracking ships at sea, and for tracking weather systems and storms.
The word “exemplified” in the passage can be replaced by _______.
Câu 11:
Read the passage, then choose the best answer by circling the letter A, B, C or D ( 15p ):
In the very distant geological past, all animals were aquatic. The very first vertebrates or animals with backbones, of which we have any fossil record, lived in water. These vertebrates, the fish, were adapted to underwater living. Their streamlined bodies were covered with scales to reduce surface friction: they had muscular tails so that they could swim swiftly in such a dense medium as water; and they were endowed with gills for breathing underwater.
Descendants of fish-type ancestors crossed the seashore barrier and accommodated themselves to life on land.
As amphibians, they possessed limbs instead of fins and lungs instead of gills. But they never became completely free of the bonds that tied them to the water; even today many amphibians return to the water to lay their eggs.
Millions of years after the first clumsy amphibians crawled over the land, newer types of land dwellers appeared, these animals give rise to the present-day reptiles and mammals. They were completely converted for land dwelling, with bodies and biological activities far different from those of fish. With these special adaptations, mammals have been able to colonize the woods and meadows, the deserts and high mountains, often far removed from the sea.
The seashore was a barrier for descendants of fish-type because …………………
Câu 14:
Read the passage, then choose the best answer by circling the letter A, B, C or D ( 15p ):
In the very distant geological past, all animals were aquatic. The very first vertebrates or animals with backbones, of which we have any fossil record, lived in water. These vertebrates, the fish, were adapted to underwater living. Their streamlined bodies were covered with scales to reduce surface friction: they had muscular tails so that they could swim swiftly in such a dense medium as water; and they were endowed with gills for breathing underwater.
Descendants of fish-type ancestors crossed the seashore barrier and accommodated themselves to life on land.
As amphibians, they possessed limbs instead of fins and lungs instead of gills. But they never became completely free of the bonds that tied them to the water; even today many amphibians return to the water to lay their eggs.
Millions of years after the first clumsy amphibians crawled over the land, newer types of land dwellers appeared, these animals give rise to the present-day reptiles and mammals. They were completely converted for land dwelling, with bodies and biological activities far different from those of fish. With these special adaptations, mammals have been able to colonize the woods and meadows, the deserts and high mountains, often far removed from the sea.
In converting to land life, animals acquired…………..
Câu 15:
Read the passage and choose the best answer.
A pilot cannot fly by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300,000 kilometers in one second. A radar set sends out a short burst of radio waves. Then it receives the echoes produced when the waves bounce off objects. By determining the time it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word “radar”, in fact, gets its name from the term “radio detection and ranging”. “Ranging” is the term for detection of the distance between an object and the radar set. Besides being of critical importance to pilots, radar is essential for air traffic control, tracking ships at sea, and for tracking weather systems and storms.
Which type of waves does radar use?
