Good morning, everyone. 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 their feet against the ground to move forward. Later, in the 1860s, pedals were added to the front wheel, but this made the bicycle difficult to ride because the front wheel was very large. It wasn't until the 1880s that the 'safety bicycle' was introduced, with two wheels of equal size and a chain drive to the rear wheel. This design, which is similar to modern bicycles, became extremely popular and led to a cycling boom in the 1890s.
❓ 根据讲座内容，前轮装有踏板的白行车存在的一个主要问题是什么？
A. A. 它们生产成本过高。
B. B. 由于前轮很大，它们很难骑行。
C. C. 它们无法在崎岖不平的道路上使用。
D. D. 他们不被允许进入城市。
✅ 正确答案
B. They were difficult to ride due to the large front wheel.