as表示“因为”，与because相比，较口语化，所表达的原因语气较弱，所表的原因比较明显，或是已知的事实。
扩展资料
例句：
As the weather is so bad, we have to delay our journey.
因为天气太糟糕，我们不得不推迟旅行。
Any new source of energy will be very welcome, as there is already a shortage of petroleum.
任何新型能源都将大受欢迎，因为石油已经出现短缺。
As luck would have it, the train was late.
不巧火车晚点了。
