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

我国华北地区降水集中于夏季，且多暴雨，使很多水资源白白流失，为使其更充分地得到 利用，采取的措施是（ ）

A．跨流域调水

B．修建水库蓄水

C．改变降水方式

D．发展节水农业