when,start,you,did,riding,nine,at,o'clock,a,bike如何连词成句,
问题描述：
when,start,you,did,riding,nine,at,o'clock,a,bike如何连词成句,
答
when did you start riding a bike ,at nine o`clock?（答：At nine o`clock）
你什么时候开始骑的自行车?九点?（或者回答是：九点）