选择填空To keep the healthy,one good way is to keep windows -so as to keep t

题目

选择填空To keep the healthy,one good way is to keep windows -so as to keep t
To keep the healthy,one good way is to keep windows _so as to keep the indoor air fresh.
A.opened B.open C.opening D.to open
请说明为什么选填A或B或C或D,

答案

选B open 在这里是形容词,表示一种状态（保持窗户开着）
open 做动词用,表示动作,如：Open the door!