办理货物运输变更或取消托运，托运人或收货人应按规定支付变更（）。
参考答案：手续费
All passengers _____ are expected to fasten the seat belts when the plane takes off and lands. [ ]
A. on aboard
B. on board
C. on the board
D. on boards
简述奥苏伯尔的有意义接受学习论。
