certainly

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。

副词 certainly:

1. definitely or positively (`sure' is sometimes used informally for `surely')
   同义词：surely, sure, for sure, for certain, sure enough, sure as shooting

1. She certainly bears you no malice.
   她对你的确并无恶意。
2. Certainly, if the weather is fine.
   如果天气好，当然可以。
3. I'll certainly be most discreet in my conversation.
   我在谈话中当然会十分小心的。
4. Certainly they must know the probable result of such speeches.
   无疑，他们一定知道这样讲话可能产生的后果。
5. He will certainly come.
   他一定会来的。

cer.tain.ly

adv.（副词）
Undoubtedly; definitely:
毫无疑问地；确定地：
例句：
This is certainly not my writing.
这肯定不是我写的字

By all means; of course:
无论如何地；当然：
例句：
You may certainly join us.
你当然可以加入我们

Surely:
确信地：
例句：
They certainly are hard workers.
他们肯定是勤奋工作的人