because 在同一句子中可不可以出现两次?GMAT句子改错题有其中的一道In recent years cattle breeders have increasingly used crossbreeding, IN PART THAT THEIR STEERS SHOULD ACQUIRE CERTAIN CHARACTERISTICS and partly because crossbreeding is said to provide hybrid vigor.a) is part that their steers should acquire certain characteristicsb) in part for the acquisition if certain characteristics in their steersc) partly because of their steers acquiring certain characteristicsd) partly

because 在同一句子中可不可以出现两次?
GMAT句子改错题有其中的一道
In recent years cattle breeders have increasingly used crossbreeding, IN PART THAT THEIR STEERS SHOULD ACQUIRE CERTAIN CHARACTERISTICS and partly because crossbreeding is said to provide hybrid vigor.
a) is part that their steers should acquire certain characteristics
b) in part for the acquisition if certain characteristics in their steers
c) partly because of their steers acquiring certain characteristics
d) partly because certain characteristics should be acquired by their steers
d) partly to acquire certain characteristics in their steers
阁下的解题思路：
先把答案a,b删掉,因为使用了in that,语气太强烈.答案c中的"because of " 使用错误. 剩下来在d和e选.由于在划线部分（大写部分）后有一个"partly because" 以平行句子的思路答案d很自然成为理想答案.可是这题的答案是“e”.问题是不是出在如果选d,句子就会同时出现两个because?
请问哪位高手可以指导一下?谢谢