DO you often go to school_____?这里为什么不能填写by a bike ,on bike ,

DO you often go to school_____?这里为什么不能填写by a bike ,on bike , how do you go to school?A by bike B on the bike -How often do you go to work by bike? -____. A.Some timesB.s I often go to work _______.A.by bike B.on a bike my sister often go to school_______是by a bike还是on the bike Do you go to work ---- A on foot B by your bike C take a bus ( )do you go to school by bike? How do you go to school? Ride a bike./By bike. "Do you often go to school by bike?"my teacher asked.(转换成间接引 I go to work on my bike,为什么是on,不能是by, Do you go to school by bus or by bike? ( )do you go to school,by bus or by bike