because, since, as和for 引导的原因状语从句

 　　1）because语势最强，用来说明人所不知的原因，回答why提出的问题。当原因是显而易见的或已为人们所知，就用as或 since。

　　I didn't go, because I was afraid.

　　Since /As the weather is so bad, we have to delay¹ our journey.

　　2）由because引导的从句如果放在句末，且前面有逗 号，则可以用for来代替。但如果不是说明直接原因，而是多种情况加以推断，就只能用for。

　　He is absent today, because / for he is ill.

　　He must be ill, for he is absent today.

1 delay   

v./ n.拖延，延误，延迟，延期；耽搁

参考例句：

• The strike caused a great delay in the delivery of the mail.这次罢工严重地延误了邮件的投递。
• I couldn't judge whether the delay was good or bad.我不能断定这样延迟是好还是坏。