certainly

certainly, surely

这两个词的含义大不相同:
1.certainly表示有信心,很肯定; surely表示相信但又感到惊奇或难以相信。有surely的句子末尾常用问号。例如:
Both of them played football better this time than they had done before, cer- tainly,Dick played splendidly.
他们俩这次比以往都踢得好,不用说, 迪克也踢得出色。
Surely that's a detective?
那人会是个侦探吗?
2.certainly用于“的确知道真实情况”的场合; surely用于有一种强烈的愿望和信任感的场合。例如:
She is late, but certainly she will come.她迟到了,但一定会来。

certainly, for certain, of course

这组词(组)都有“确实地,一定地,当然地”的意思。它们的区别是：
certainly可位于句首或句末,表示强调,有时位于动词前,修饰全句,表示确有把握,深信不疑; of course通常用于表示自然的或不可避免的结果; for certain指确有把握,经常用于否定句中。例如:
She certainly thought that this doctor was overestimating her case.
她确实认为这医生夸大了她的病情。
You could of course have criticized him, but,instead,you cried him down rudely.
你批评他当然是可以的,可你却粗暴 地把他贬低。
I can't say for certain when he will arrive.
我说不准他什么时候到达。

certainly，naturally，of course，surely

这些副词或词组均有“肯定地，当然”之意。
certainly强调有把握，深信不疑。
naturally指自然而然，毫无造作或天生如此。
of course指毫无疑问，自然如此。可与certainly和naturally换用。
surely表一种必然的可能性，也可表示信心或不轻信。强调主观判断。