______terrible the weather is these days!
 

地球半径约为6400000米，则此数用科学记数法表示为（   ）

阅读下面的古诗。
                                                                                                                                                  画眉鸟
                                                                                                                                                  欧阳修
                                                                                                                         百啭千声随意移，山花红紫树高低。
                                                                                                                         始知锁向金笼听，不及林间自在啼。