北京“坊”间分界线的构成包括( )。

A．主干大街

B．支干在街

C．河道水系

D．皇城

E．宫城

F．内外城墙

How are you going on with your English?（）

A.I am very well. 

B.I am going to the library. 

C.I am going to take College English Test Band Four. 

D.That's a good question