1.because连词，引导原因状语从句
He can’t come because he is ill.他因病不能来。
I got a job because I worked hard.因为工作努力，我得到了一份工作。
2.because of介词短语，引导名词或代词作状语
He can’t come because of his illness.他因病不能来。
I got a job because of my hard work.因为工作努力，我得到了一份工作。
【提示】 强调原因状语时，只能强调because和because of引导的状语。
It was because I worked hard that I got the job.是我工作努力才得到了这份工作。
It is because of his illness that he can’t come.是因为有病他才不能来。