2、°,∠E=30°,则的度数为()A. B. C. D.____________________________________________________________________________________________________________________________4.函数的自变量x取值范围是()A.x≠2B.x≠0C.x≠0且x≠2D.x>25.如图,已知AB为⊙O的直径,点C在⊙O上,∠C=15°,则∠BOC的度数为()A.15°B.30°C.45°D.