of the intrinsic differences that separate amarican from english the chief have their roots in the obvious disparity between the environment and traditions of the american people since the seventeenth century and those of the english.

參考答案:

本句正常語序為：the chief of the intrinsic differences that separate amarican from english have their roots in the obvious disparity between the environment and traditionsof the american people and those of the english since the seventeenth century.
"that separate amarican from english" 做定語從句，"since the seventeenth century" 為時間狀語，這兩處譯成單句，使譯文通順，易于理解。

譯文：美語之所以區(qū)別語英語是由本質(zhì)上的差異決定的，而主要差異的根源在于兩個不同的社會環(huán)境和不同的文化傳統(tǒng)。自17世紀以來，美國人和英國人在這兩個方面的差異是很明顯的。