绘制一张学校平面图,采用下列比例尺最适合的是( )
A:1:1000
B:
C:4km
D:图上1厘米代表实地距离2千米
— What time shall we leave for the airport? — It's foggy today. I'm not sure __________ be closed soon. Let's go now.
若AB=10,BC=12,当PD∥AB时,求BP的长.