A:30°
B:35°
C:40°
D:50°
若向量a→=(1,1),b→=(2,5),c→=(3,)满足条件(8a→—b→)·c→=30,则x= ( )
第二次世界大战亚洲策源地形成的标志是( )
His aunt____ (唱歌) very well.