—It's a chair.
A:What's your name?
B:What's this?
C:Is this a chair?
I am going camping with my friends tomorrow.
如图,直线l1∥l2,点A在直线l1上,以点A为圆心,适当长为半径画弧,分别交直线l1、l2于B、C两点,连结AC、BC.若∠ABC=56°,则∠1的大小为( )