摘要：3．All passengers are expected to fasten the seat belts when the plane takes off or lands. A．on the board B．on board C．on boards D．on a board
网址：http://m.1010jiajiao.com/timu3_id_2560697[举报]
All passengers________are expected to fasten the seat belts when the plane takes off or lands.
[ ]
A. on the board
B. on board
C. on boards
D. on a board
查看习题详情和答案>>
B. on board
C. on boards
D. on a board