Expressing "since" with "jiran"

既然 (jìrán) means "since", and is often followed by 就 to mean "since...then...". It is used like this:

Structure

既然 + fact + 那/就/那就 + suggestion/inference

This construction is not generally used to express a result, but more of a suggestion or inference deduced from the first fact.

她既然刚生了孩子，那她一定很累吧。 Since she just gave birth to a child, she is definitely tired. (an inference)
他的关系既然那么硬，那他肯定能帮我们吧。Since his relationship his so strong, he can definitely help us. (an inference)
他既然那么有钱，那干吗不能把一部分财产捐给慈善机构呢？Since he has so much money, why wouldn't he be able to donate some to charity? (a suggestion)
既然大家的意见一致，那最好趁早行动！Since it's unanimous, it would be best to tak action as soon as possible. (a suggestion)
你既然不想说，那就算了吧。Since you don't want to speak, just for get it. (a suggestion)