1、The concept of assessment reference period is put forward. The relation among exceeding probability, recurrence period and annual mean incidence of intensity is deduced.
2、Single or small amount of multiple condyloma feasible treatment, multiple or large area of condyloma can be treated 2-3 times, generally in the recurrence period of 20 days -3 months.
3、Parapet wall is set on top of breakwater and is designed according to the wave basically can not pass over under the sea conditions of a-hundred-year recurrence period.
