All passengers _____ are expected to fas
问题:
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
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