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.
❓ 강의에 따르면, 앞바퀴에 페달이 부착된 자전거의 주요 문제점은 무엇이었나요?
A. A. 그것들은 너무 무거워서 움직일 수 없었다.
B. B. 불안정성 때문에 타기가 어려웠다.
C. C. 그들은 브레이크가 없었다.
D. D. 그것들은 생산하기에 너무 비쌌다.
✅ 正确答案
B. They were difficult to ride due to instability.