In addition to the internal variability of the global climate system itself, there is the added factorof external influences, such as volcanoes and solar activity.
除了全球气候系统本身的内部变化之外，还有外部影响的附加因素，如火山和太阳活动。
2
Of course, the most important factor in determining what's the best cross training activity for you is whether or not you like it.
当然，在确定什么是最适合你的交叉培训活动中最重要的因素是你是否喜欢它。
3
So the trick is to compare the activityof your typical user with the activity described in the tests in part 1 and 2 of this series, and work out a rough scaling factor.