bicycle motocross(自行车越野赛)为什么简写成BMX?X是哪来的?对这个事情,一直纳闷!

bicycle motocross(自行车越野赛)为什么简写成BMX?X是哪来的?对这个事情,一直纳闷! 爱运动自行车行 的英文这样写对吗：love sports bicycle shop.正确的应该怎么写到底哪个是对的？ how can you tell whether you are a good rider.的翻译是“你怎么才能判断你是否是一个好的自行车手完形填空Perhaps you ride a bicycle to school. Riding a bicycle can be great fun. Do you know how to ride a bicycle 1 ?Carefu bicycle同义词 on the bicycle 与 by bicycle 区别 英语单词bicycle怎么读 bicycle英文怎么读 bicycle的简写词 () ride your bicycle here! Can you ride bicycle? the bicycle cost $250 bicycle的同类词 bicycle什么意思 no bicycle是什么意思 bicycle的同义词是什么? bike和bicycle区别 bicycle和bike区别 Bicycle的中文是什么