曲柄滑块机构动画:because和because of的用法区别

because of 相当于一个介词短语，后面只能跟名词性的词.
而because 后面必须跟句子.

A traditional rule holds that the construction the reason is because is redundant, and should be avoided in favor of the reason is that. The usage is well established, however, and can be justified by analogy to constructions such as His purpose in calling her was so that she would be forewarned of the change in schedule or The last time I saw her was when she was leaving for college. All three constructions are somewhat less than graceful, however. · When because follows a negated verb phrase, it should be preceded by a comma when the because clause explains why the event did not occur. He didn't marry her, because she was frivolous means roughly, “Her frivolity was his reason for not marrying her.” When no comma is used, the because clause is understood as part of what is being negated. He didn't marry her because she was frivolous means roughly, “His reason for marrying her was independent of her frivolity.”

传统的原则认为结构the reason is because 太累赘，应避免，而赞同使用 the reason is that 。 这种用法被广泛地接受，并可以用类似的结构证明是正确的，如他 呼唤她 的目的是以便 她能预先知道时间安排的改变 ，或者 最近 一次 我看见她是 当 她正要去学院时。 然而所这三种结构都有不够完美的地方。当because 跟着一个否定动词短语时， 该在它前面加一个逗号来表示这个because 从句解释的是为什么这件事 没有 发生。 他不娶她，因为她很轻浮。 粗略的意思是， “她的轻浮是他不娶她的原因。”当没有用逗号时，这个because 从句被理解为被否定的部分。 他不娶她不是因为她轻薄， 粗略的意思是， “他和她结婚的原因与她的轻薄无关。”

金山词霸这么说。