Becasue (of) ...
Due to...
Becaue of/(Due to) my mistake,we lost the opportunity.
As...
As you are busy,I’ll go out by myself.既然你很忙,我就单独外出吧.
Since...
Since the problem hasn't been sloved for such a long time,we have to escalate it to higher level.由于这个问题长时间没有得到解决,我们只好向更高一级报.