A:①③
B:①④
C:②③
D:②④
乘火车。
小旭和爸爸、妈妈坐火车去玩,一张成人车票8元,小旭买的是半价票,全家来回一共花了____元钱。
Tom and his sister ______ to the barbecue last Saturday.They were very happy.
要改变直流电动机的旋转方向,可行的办法是( )
地图的“语言”是比例尺____和____.