Câu hỏi:
06/11/2020 234Read 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 38 to 42.
HISTORY OF THE HELICOPTER
Although first flight generally attributed to a fixed-wing aircraft, the helicopter actually represents the first style of flight envisioned by humans. The ancient Chinese developed a toy that rose upward when spun rapidly. As early as the mid-sixteenth century, the great Italian inventor Leonardo da Vinci had drawn a prototype for the machine that we now know as the helicopter.
Early in the twentieth century, a great deal of experimentation and revision was taking place with regard to helicopter flight. The well-known phrase “two steps forward and one step back” provided an apt descriptor for early flight development. Uneven lift, known as dissymmetry, caused the early helicopters to flip over and confounded the inventors until the creation of the swash-plate; this allowed the rotor blade angles to be changed so that lift would be equal on each side of the shaft.
On November 13, 1907, the French pioneer Paul Cornu made history by lifting a twin-rotor helicopter into the air for a few seconds without ground assistance. Several models followed without significance until in 1924 when another French pioneer, Etienne Oehmichen, became the first to fly a helicopter for one kilometer. It was a historic flight of 7 minutes and 40 seconds. By 1936, solutions have been found to many of the problems with helicopter flight.
With the introduction of the German Focke-Wulf Fw 61, the first practical helicopter became a reality.
Why was “dissymmetry” important to the early pioneers of helicopter flight?
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).
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Trả lời:
Đáp án A
Tại sao “tính không đối xứng” lại quan trọng với những chiếc máy bay trực thăng trước đây
Đáp án nằm ở dòng 3, 4 và 5 đoạn 2: “Uneven lift, known as dissymmetry, caused the early helicopters to flip over and confounded the inventors until the creation of the swash-plate; this allowed the rotor blade angles to be changed so that lift would be equal on each side of the shaft.”
CÂU HỎI HOT CÙNG CHỦ ĐỀ
Câu 1:
It is very important for a firm or a company to keep _____ the changes in the market.
Câu 3:
Mark the letter A, B, C, or D on your answer sheet to indicate the word whose underlined part differs from the other three in pronunciation in each of the following questions
Câu 4:
We couldn’t help laughing when he took _____ his teacher so well.
Câu 5:
_____ are unpleasant, but it will be nice when we get into the new house.
Câu 7:
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.
Usually the climate in mountainous areas becomes much windy at higher altitudes.
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