From the last three paragraphs we know the fact that ______.
A.
in Beijing, lengthening the existing 53-kilometer subway is among the 50 large projects
B.
a 40.5-kilometer line will be added to Beijing's first light railway
C.
the length of the subway will be up to 135.25 kilometers in 2005
D.
a 70-meter-wide green belt will supply us with enough water