now that除了表示原因外，还含now的`意思，意思是“既然(现在)……”“既然(当时)……”。
例句：
Now you're settled, why don't you take up some serious study?
既然你(现在)已经安顿下来了，为什么不开始正经地学点东西呢?
Now that she was retired she lived with her sister.
现在她已经退休了，和姐姐一起住。
Now that he’s got this job, there’ll be no holding him back .
既然他现在已经得到了这份工作, 就没有什么能制约他的了。