The pilot asked all the passengers on board to remain ________ as the plane was making a landing. [      ]

A. seat  

B. seating

C. seated  

D. to be seating

关于微囊特点叙述错误的是()。

A．微囊化制剂可避免肝脏的首关效应

B．微囊可提高药物的稳定性

C．微囊制剂可使药物浓集于靶区

D．微囊可控制药物的释放

E．微囊可掩盖药物的不良嗅味