原句案例：
The tropics contain a larger surface area of land than higher latitudes——a fact that is not always evident when we examine commonly used projections of Earth's curved surface, since this tends to exaggerate the areas of land in the higher latitudes——and some biogeographers regard the differences in diversity as a reflection of this effect.
词汇讲解：
tropics n. 热带
projection n. 发射，投射;
exaggerate /ɪg'zædʒəreɪt/ v. 夸张，夸大
结构划分：
The tropics contain a larger surface area of land than higherlatitudes——(a fact) (that is not always evident) (when we examine commonly used projections of Earth's curved surface), (since this tends to exaggerate the areas of land in the higher latitudes)——and some biogeographers regard the differences in diversity as a reflection of this effect.
深度分析：
这个句子的主干就是一个并列结构，中间被一个破折号隔开了。
The tropics contain a larger surface area of land than higher latitudes and some biogeographers regard the differences in diversity as a reflection of this effect.
修饰一：(a fact) ，同位语
中文：一个事实
修饰二：(that is not always evident) ，从句
中文：不总是那么明显
修饰三：(when we examine commonly used projections of Earth's curved surface) ，从句
中文：当我们在仔细观察通常所用的地球曲面投影时
修饰四：(since this tends to exaggerate the areas of land in the higher latitudes) ，从句
中文：因为这往往夸大了高纬度的土地面积
参考翻译：
热带比高纬度包含更大的的土地面积——当我们在仔细观察通常所用的地球曲面投影时，这一事实并不总是显而易见的，因为这往往夸大了高纬度的土地面积——并且一些生物地理学家认为多样性的差异反映了这一影响。
以上就是托福阅读中长难句的训练分析介绍，希望大家能够学到有效的训练和提升方法，让自己更为轻松地面对长难句得到高分。
