C:2A ( g ) + B ( g ) =' 2C' ( l )△H3
A:2A ( l ) + B ( l ) =' 2C' (g )△H1
B:2A ( g ) + B ( g ) =' 2C' (g )△H2
D:2A ( l ) + B ( l ) =' 2C' ( l )△H4
如图,在四边形ABCD中,EF∥BC,FG∥AD,则 =____.
图为人体部分生理活动图,图中b排出人体的途 径有( )条