Câu hỏi:
14/07/2023 943
Choose from A, B, C, or D the one that best answers each of the questions in the following passage.
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?
Choose from A, B, C, or D the one that best answers each of the questions in the following passage.
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.
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Trả lời:
Giải bởi Vietjack
Chọn A
Câu hỏi cùng đoạn
Câu 2:
According to the passage, what can radar detect besides location of objects?
Đáp án chính xác
Lời giải của GV VietJack
Chọn C
Câu 3:
The word “exemplified” in the passage can be replaced by_________.
Đáp án chính xác
Lời giải của GV VietJack
Chọn C
Câu 4:
The word “shouts” in the passage most closely means_________.
Đáp án chính xác
Lời giải của GV VietJack
Chọn B
Câu 5:
Which of the following words best describes the tone of this passage?
Đáp án chính xác
Lời giải của GV VietJack
Chọn B
Câu 6:
According to the passage, the distance between a radar set and an object can be determined by_________.
Đáp án chính xác
Lời giải của GV VietJack
Chọn D
Câu 7:
Which type of waves does radar use?
Đáp án chính xác
Lời giải của GV VietJack
Chọn D
Câu 8:
The word “tracking” in the passage most closely means_________.
Đáp án chính xác
Lời giải của GV VietJack
Chọn B
Câu 9:
Which of the following would most likely be the topic of the next paragraph?
Đáp án chính xác
Lời giải của GV VietJack
Chọn B
Câu 10:
What might be inferred about radar?
Đáp án chính xác
Lời giải của GV VietJack
Chọn B
Nhà sách VIETJACK:
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