because of意为"由于,因为",强调因果关系,在句中仅作状语,修饰句中的一部分,与其他成分不用逗号隔开.如：We must not get discouraged because of such a minor setback．
我们决不可因为这样一个小小的挫折而灰心丧气.
on account of与because of 同义,但语气较为正式.可作状语、表语,不作定语.如：
He could not come on account of his illness．他因病不能前来.
That was on account of lack of exercise．那是由于缺乏锻炼.