It is required that passengers remain when the plane is taking off or landing.A. sitB. se

问题补充：

It is required that passengers remain when the plane is taking off or landing.

A. sit

B. seating

C. sat

D. seated

答案：

A. sit

B. seating

C. sat

(答案→)D. seated

解析：考查形容词用法。Seated是过去分词转换的形容词，与系动词连用形成系表结构。Remain seated就坐，坐着；句意：据要求，当飞机起飞的时候，所有的乘客都要坐在位置上。故D正确。