记忆技巧：in 使…；加以…；饰以… + cid 落下 + ence 表行为 → 使掉下来 → 事情发生
1.The incidence of breast cancer increases with age.
2.The change in smoking is paralleled by a change in the incidence of lung cancer
3.The incidence of this disease has dropped considerably in the past few years.
4.It was noted that within a year the incidence of illness had increased quite significantly.
5.There's a high incidence of disease.