经纬仪是测定角度的仪器，它既能观测水平角，又可以观测竖直角。
参考答案：对
— Mum!Alice has broken my CD player!
— ________After all, she couldn't have done it on purpose. [ ]
A. What's the matter?
B. It doesn't matter.
C. No trouble at all.
D. How come?
骑自行车的人，遇到紧急情况刹车时，用力捏闸，其目的是为了[ ]
A、增大压力以增大摩擦
B、使接触面粗糙以增大摩擦
C、减小摩擦
D、以上说法都不对
