They even have an IELTS mock speaking test course, great practice for all students preparing for IELTS.

他们甚至有雅思模拟口语考试课程，适合所有备考雅思考试的学生的绝佳练习。

Because of changes in the genetic material (mutations) these have new characteristics and in the course of their individual lives they are tested for optimal or better adaptation to the environmental conditions.

由于遗传物质的变化（突变）， 它们具有新的特征， 并且在它们的个体生命过程中， 它们经过测试以最佳或更好地适应环境条件。