Good morning, everyone. Today we're going to discuss the history of the bicycle. Now, many people believe the bicycle was invented in the 19th century, but in fact, early prototypes appeared as far back as the 15th century. However, the first practical two-wheeled vehicle, called the 'draisine', was created by a German baron in 1817. It had no pedals; riders pushed their feet along the ground. The major breakthrough came in 1860s in France, when pedals were added to the front wheel. But this design was unstable because of the large front wheel. It wasn't until the 1880s that the 'safety bicycle' with a chain drive and equal-sized wheels became popular, making cycling much safer and more accessible to the general public.
❓ Vấn đề chính của những chiếc xe đạp có bàn đạp gắn ở bánh trước là gì?
A. A. Chúng quá nặng để có thể đạp lên dốc.
B. B. Chúng không ổn định do bánh trước quá lớn.
C. C. Chúng khó điều khiển vì truyền động bằng xích.
D. D. Họ yêu cầu người đi xe phải dùng chân đẩy dọc theo mặt đất.
✅ 正确答案
B. They were unstable due to the large front wheel.