His left foot is on the pedal. His right foot is on the ground. He pushes down on the pedal. He takes his right foot off the ground. He puts it on the pedal. The pedals start to go around. They go around in a circle. His knees go up and down. The bicycle rolls forward.
他的左腳踩在踏板上了。他的右腳在地上。他踩著踏板。他把右腳從地上掉下來。他把它放在踏板上。踏板開始四處走。他們繞著一圈。他的膝蓋上下了。自行車向前滾動。
他的左腳踩在踏板上了。他的右腳在地上。他踩著踏板。他把右腳從地上掉下來。他把它放在踏板上。踏板開始四處走。他們繞著一圈。他的膝蓋上下了。自行車向前滾動。