Average cost of the system queries that could be reduced by the index in the group.

可通过组中的索引减少的系统查询的平均成本。

youdao

Full digital keyboard benefits the group control of elevators, but makes the cost of system hardware increased.

而全数字键盘虽然可以对电梯实施更好的调度，但是硬件的安装增加了电梯系统的成本。

youdao

This rule tells us that an enormous amount of the health system cost is centered in a very concentrated group of people.

FORBES: Why 5% of Patients Create 50% of Health Care Costs