A:水能资源丰富
B:气温南高北低
C:河流滚滚东流
D:东部降水丰富
He found _______ wrong _______ him to drop litter carelessly in the park.
取一根火柴梗横放入酒精灯火焰中,约1—2秒,火柴梗最先炭化的是( )
如图△ABC的内接圆于⊙O,∠C=45°,AB=4,则⊙O的半径为( )