Jack's made few mistakes in his exam, ______?
A:hasn't he
B:has he
C:isn't he
D:is he
如图,中国的山顶洞人,在兽牙、海蚌壳等东西上钻出小孔,做成项链,见下图,这说明山顶洞人已有了( )
如图,在△ABC中,AB=AC,∠A=40°,ED为AB垂直平分线,则∠EBC的度数是( )
如图,⊙O外接于△ABC,AD为⊙O的直径,∠ABC=30°,则∠CAD=( )