按题意要求，每一横行成等差数列，每一纵列成等比数列填表如图，故a=

1

2

，b=

3

8

，c=

1

4

，则a+b+c=

9

8

．
故选：D．
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1	2	3	4
0.5	1	1.5	2
0.25	0.5	0.75	1
0.125	0.25	0.375	0.5
0.0625	0.125	0.1875	0.25