兩個半徑相同的金屬小球,帶電量之比是1:5,當它們相距r時作用力大小為F1,若把它們互相接觸后再置于原來的位置上,作用力大小為F2,則F1:F2可能為(                              )                                   

    A.            5:1                 B. 5:9           C. 5:4       D. 5:8

                                                                                                                                     

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