the poilt asked all the passengers on board to remain as the plane was making a landing

Question

A seat  B seating C seated   D to  be seating 

Answer 1

The pilot asked all the passengers on board to remain (seated) as the plane was making a landing. 翻译：当飞机马上要降落的时候，驾驶员请飞机上所有乘客坐好并系好安全带。
本题选C。原因是：
首先，remain是一个系动词，所以在思考时不妨把它替换为be来看，这样解题会简单一点。另外，seat只有seated这样一种形式表示坐着的状态。所以综上，remain seated 为系表结构，而并不是有被动色彩的意思。
此外，一些表示情绪、情感的过去分词作表语和定语时也不具备被动色彩。例如：
He felt puzzled at what she said. 听了她的话，他感到很迷惑。
The excited people finally cooled down.激动的人们终于冷静了下来。

Answer 2

C。 sit down,please
相当于Be seated ,please，一般这个词都不用进行时