• 例1：He was late because he got up late. （因为他起晚了，所以迟到了。）（because突出“原因”）
• 例2：As you were out, I left a message. （因为你不在，所以我留了⼀张字条⼉。）（as突出“主从关系对等”）
• 例3：We thought that, since we were in the area, we'd stop by and see them. （我们想，既然到了这个地⽅，就该顺便去看看他们。）（since本意“⾃从、此后”，突出“时间先后”）