The student didn't find much _________ about the topic on that website.
A:report
B:article
C:information
D:story
如图,在菱形ABCD中,若∠B=60°,点E、F分别在AB、AD上,且BE=AF,则∠AEC+∠AFC的度数等于( )
读甲、乙两国示意图,回答下列各题。
如图,圆C中,弦AB的长度为4,则AB→•AC→=( )