复数： incidences

Unfortunately , the exact incidence of these memory problems isn 't known .

不幸的是，记忆问题的具体发生率并不清楚。

But there is good historical data on the incidence and location of earthquakes .

但我们掌握着大量有关地震发生几率与发生地点的历史数据。

There were large changes in symptom incidence through the cycle for all symptoms .

整个周期内，所有的症状的发生率都有很大的变化。

A different scientific approach looks at the effect of certain lifestyle modifications on the incidence of disease .

另一种科学途径着眼于特定生活方式的改善对于疾病发生率的影响。

While the climate warmed slightly last century , the incidence of hurricanes and cyclones fell .

尽管气候在上世纪微微变暖了，飓风与台风的发生次数反而减少了。