既然我们要等几分钟火车，我们喝杯咖啡吧。

___Since we've got a few minutes to wait for the train, let's have a cup of coffee.

因为我母亲明天要做手术，我将不能来上您的课了。

___Since my mother has surgery tomorrow, I will not be able to come to your class.

因为在下雨，我们应该待在室内。

___Since it's raining, we should stay indoors.