Friedman's pricing formula takes into account square footage, cleaningfrequency, and "population density."
Friedman的服务价格将面积，频率，甚至“人口密度”都计算在内。
2
On condition that the water production is ensured, optimal cleaningfrequency and minimum cleaning cost could be obtained by choosing the appropriate cleaning strategy and time.
在保证产水量的情况下， 选择恰当的清洗策略和清洗时机可使清洗次数最合理， 清洗费用最低。
3
This means that the Settings for frequency and duration should ensure there is no overlap between a cleaning procedure's finish time with another one's start time.