If some areas should suffer major physical changes know that it is not a randomoccurrence.
如果一些地方需要经历些主要的物理改变，要知道那不是一个偶然事件。
2
Mimicry arises as the result of evolution through natural selection and the occurrence of random genetic mutations that lead over many generations to the appearance of favorable characteristics.
拟态是无数代自然选择和遗传变异的进化而获得的有利特征的结果。
3
There are many kinds of fault happening during the test and the occurrence of faults is highly random. All these bring great difficulties to test personnel.