[问答题]
A 21-speed bicycle has sea;k1c:giu g zum2 uq.xm6 ,:bxven sprockets at the rear wheel and th ykv u3vur/y05ree at the pedal cranks. In which gear is it harder trv/ku3u yy50 vo pedal, a small rear sprocket or a large rear sprocket? Why? In which gear is it harder to pedal, a small front sprocket or a large front sprocket? Why?
