如图,已知AB是⊙O的直径,直线CD与⊙O相切于点C,AC平分∠DAB. 求证:AD⊥DC.若AD=2,AC=,求AB的长
Look at that ruler. ______ ruler is green.
Is ________ your aunt? What’s ________ name?
-----How _______ your mother? ------She is fine.
--____ is your pen?-- It’s_____.
My father and mother are my____.