Good morning, class. Today we're going to discuss the history of the bicycle. The first bicycle, invented in the early 19th century, had no pedals. Riders pushed themselves along with their feet. Later, in the 1860s, pedals were added to the front wheel. This design was called the 'boneshaker' because it was very uncomfortable on rough roads. In the 1880s, the 'safety bicycle' was introduced, featuring two equal-sized wheels and a chain drive, which made riding much safer and more efficient. This design became the basis for modern bicycles.
❓ 19世纪80年代安全自行车的主要改进是什么?
A. A. 它在前轮上增加了踏板。
B. B. 它有两个大小相同的轮子和一个链条传动装置。
C. C. 它更轻便,更容易携带。
D. D. 它有一个辅助电机。
✅ 正确答案
B. It had two equal-sized wheels and a chain drive