because 连词, “因为”，用来连接原因状语从句。

例如： I did it because he told me to.我做这事是因为他叫我做的。

Just because I don’t complain, people think I’m satisfied. 因为我没发牢骚，人们就以为我心满意足了。

because of介词短语，“因为(某人/某事物);由于”，在句中作状语。

例如： They are here because of us.他们是为了我们而来到这里的。

He walked slowly because of his bad leg.他走得慢是因为腿有毛病。

because of　和because的意思都是“因为”，区别在前者跟短语，后者跟从句。

例如： 他们因为下雨没去博物馆。可用because和because of两种方法表示。

They didn’t go to the museum because of the rain.

They didn’t go to the museum because it rained.

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