Good morning, class. Today we're going to discuss the history of the bicycle. Now, many people assume the bicycle was invented in the 19th century, and that's partly true. The first two-wheeled vehicle, called a draisine, appeared in 1817, but it had no pedals. It was essentially a wooden frame with two wheels, and riders pushed themselves along with their feet. The real breakthrough came in the 1860s when pedals were attached to the front wheel. However, these early bicycles were very difficult to ride because the front wheel was large, making them unstable. It wasn't until the 1880s that the chain drive was introduced, which allowed the rear wheel to be powered, creating a much safer and more efficient design. This design, known as the safety bicycle, quickly became popular and is the basis for modern bicycles.
❓ Theo bài giảng, 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 di chuyển.
B. B. Chúng khó điều khiển do không ổn định.
C. C. Chúng không có phanh.
D. D. Chúng quá đắt để sản xuất.
✅ 正确答案
B. They were difficult to ride due to instability.