When can I t______ on the plane?
太广泛了!想要填什么都可以(只要有道理/意义; "make sense").例如:
(1) When can I "telephone" on the plane?(飞机内使用电话)
(2) When can I "talk on" the plane?(谈关于飞机...)
(3) When can I "take on" the plane (处理飞机?雇用飞机?不是很正确!)