求教by的用法~ prep老1-105 各位高人帮帮忙吧！！！

cynthia627

105. (30121-!-item-!-188;#058&004107)
Even though it was not illegal for the bank to share its customers' personal and financial information with an outside marketing company in return for a commission on sales, the state's attorney general accused the bank of engaging in deceptive business practices by failing to honor its promise to its customers to keep records private.
(A) by failing to honor its promise to its customers to keep
(B) by its failure of honoring its promise to its customers to keep

(C) in its failing to honor its promise to its customers of keeping

(D) because of its failure in honoring its promise to its customers in keeping

(E) because of its failure to honor its promise to its customers of keeping

OMA：A

这道题我可以选对。但是第二遍看，我有点疑惑by的用法。这里面的by显然与because of有些区别。但是我也说不出来。能不能请哪位高人指点一下，到底by的用法是怎么回事？与because of的区别什么捏？ 恭候赐教啊！！！

cynthia627

努力地顶顶~

lpdeng

我对by的用法也有很多疑问。 等候nn解答！

对于becasue of 与 by 的区别，说说我的理解。
1）because of 后面不加现在分词。 但要注意区分动名词和现在分词。
2）ecasue of 表示 因为什么什么。 by 表示通过/用什么什么（来达到）

请nn指正！

cynthia627

我在自己顶顶吧~ 高手！请出招！！！