by train 乘坐火车,介词by+交通工具名词（中间不用冠词）,只能作状语take a/the train 乘坐火车,动词短语,可以作谓语例如：He usually goes to school by train.=He usually takes a/the train to school.祝你开心如...那为什么My mother goes to work () her bike, but I go to school ( ) bus. A in;on B by;by C on;byDby;on 选c而不选b呢介词by+交通工具名词（中间不用冠词,也不用人称代词），on one's bike=by bikeby bus= in a busby ship= on a ship