已知a＞b＞c，且
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a＞b＞c，且
+9 a-b
+1 b-c
≥0恒成立，k c-a
∴
≤k a-c
+9 a-b
，1 b-c
两边同乘以a-c得，k≤(a-c)(
+9 a-b
)，1 b-c
又(a-c)(
+9 a-b
)=(a-b+b-c)(1 b-c
+9 a-b
)=10+1 b-c
+9(b-c) a-b
≥10+2a-b b-c
=16．
×9(b-c) a-b a-b b-c
∴k≤16．
则实数k的最大值为16．
故选B．
What do the people usually do on weekends? Some people like to at home, but others like to go out for a walk or play football. Mr Smith hard in a factory during (在期间) the . On the weekends, he usually the same thing. On Saturday he washes his car and on he goes with his family to a village(村庄) by car. His uncle and aunt a farm there. It isn't a big one, but there is always to do on the farm. The children help with the animals and give them some . Mr and Mrs Smith help in the field(田地). At the end of the day, they are all and Mr Smith's aunt them a big meal.
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