There is an association between airquality levels and the incidence of pulmonary disease in the world's cities . 在世界大城市中，空气污染水平和肺病发病次数之间存在着某种关系。
If you were of an observant turn it might have struck you that he blinked much less often than most of us . 假如你善于观察，你也许会注意到：他眨眼睛的次数要比咱们大多数人少得多。
Rainfall frequency and amount are thus crucial factors in determining the position of deposition in a soil profile . 降雨次数和降雨量是左右溶质在土壤剖面中沉积位置高低的决定性因素。
The degree of mixing and the rate of approach to uniformity will depend on the frequency of turnover of solids . 混合的程度和达到均匀混合的速度，将由固体颗粒在单位时间内翻转的次数来决定。
Because the larger the event, the larger the number of oscillations of the transducer before they decay below the trigger level . 因为事件越大，传感器在它衰减到低于触发器电平之前的振荡次数越多。
With the terrible images ofafrican famine still fresh in mind, it is hard to believe that the occurrence of famine is declining . 由于人们对非洲饥荒的可怕形象记忆犹新，因此很难相信饥荒发生的次数在下降。
Self-dialing has somewhat reduced the number of calls the operators handle, but it has by no means eliminated them completely . 直接拨号可减少话务员所要应付的电话次数，但这绝不等于完全取消了她们的话务工作。
The earth in moving around the sun, would impinge on move particles which are coming from its forward side than from its hind side . 地球绕太阳运行时，它与从前面射来的粒子相碰撞的次数，将比从后面射来的粒子要多。
The median is not as highly influenced by the frequency of occurrence of a single value as is the mode, nor is it pulled by extreme values as is the mean . 中位数既不象众数那样受到数值出现次数的影响，又不象平均数那样随着特殊值的大小而偏移。
The minimum number of times the particle can occur 粒子可发生的最小次数。 （从
