Good morning, class. Today we're discussing the history of the bicycle. The modern bicycle, as we know it, emerged in the late 19th century, but its predecessors were quite different. In 1817, a German inventor created a wooden frame with two wheels, which riders pushed along with their feet. This was called the 'draisine'. Later, in the 1860s, pedals were added to the front wheel, leading to the 'penny-farthing' with its huge front wheel. However, it wasn't until the 1880s that the 'safety bicycle' with a chain drive and equal-sized wheels became popular, making cycling safer and more accessible to the general public.
❓ Đặc điểm chính nào của 'xe đạp an toàn' đã làm cho nó dễ tiếp cận hơn?
A. Khung gỗ và lực đẩy bằng chân
B. Một bánh trước khổng lồ có bàn đạp
C. Bộ truyền xích và các bánh xe có kích thước bằng nhau