Câu hỏi:
25/04/2023 530
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 1 to 7
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?
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 1 to 7
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?
Đáp án chính xác
Câu hỏi trong đề:
Trắc nghiệm tổng hợp Tiếng anh có đáp án 2023 !!
Sách mới 2k7: Tổng ôn Toán, Lí, Hóa, Văn, Sử, Địa…. kỳ thi tốt nghiệp THPT Quốc gia 2025, đánh giá năng lực (chỉ từ 110k).
Quảng cáo
Trả lời:
Giải bởi Vietjack
Lời giải:
Giải thích:
1. Tác giả bàn về nguyên lý làm việc của radar trên máy bay.
Đáp án: A
Nhà sách VIETJACK:
CÂU HỎI HOT CÙNG CHỦ ĐỀ
Câu 1:
We were lost in the forest, _______ luckily my friend had a map in his backpack.
Xem đáp án »
26/04/2023
16,491
Câu 2:
My cousin and I ______ on the computer when there was a power cut.
Xem đáp án »
26/04/2023
15,608
Câu 4:
This is the most delicious cake I've ever tasted. - I've never _________________.
Xem đáp án »
26/04/2023
12,942
Câu 6:
Jenny often ________ jeans and T-shirt at school but she ________ a gorgeous dress today.
Xem đáp án »
25/04/2023
8,782
Câu 7:
Rewrite the sentence
The unemployment rate is getting higher, so the crime rate is becoming higher as well.
Rewrite the sentence
The unemployment rate is getting higher, so the crime rate is becoming higher as well.
Xem đáp án »
13/07/2024
8,033
về câu hỏi!