当然的英文：
only natural
as it should be
certainly
of course
without doubt
You betcha

参考例句：

Of course.
当然感兴趣。

Of course
当然,自然,无疑

Oh yes, I will.
嗯，我当然同意。

It is not, of course, exhaustive
当然这是不够详尽的。

However, some people prefer jasmine tea.
当然有些人喜欢茉莉花茶。

`Certainly, from the keel to the truck of the masts, all the wood, that is.'
“当然了，当然了，一言为定，从上到下，所有‘木柴’，都归您！”

I definitely will give my consent to your plan.
我当然同意您的计划。

Well, you are always heroic and transcendental
当然，你一向是勇敢而超凡入圣的。

That is no argument for managerial complacency.
当然管理当局绝对不能够太过自满

They postulate excessive increase in price.
他们把物价过度增长视为当然。

natural是什么意思：
adj. 自然的；天然的；不做作的；天生的；原始的；有血缘关系的
n. 天然物；生就具有特定才能的人

natural | natural sign
白键|本位记号

The method is a natural.
这方法一定灵。

Is there necessity in nature?
自然界是否存在必然性？

should是什么意思：
aux.v. 应该，应当；本应，本当；假如，万一；可能，可以

Should there be a flood, what should we do?
万一发生水灾我们怎么办？

You should do as the law prescribes.
你应该按照法律的规定做。

You should consider his youth.
你应体谅他的年轻。

certainly是什么意思：
adv. 无疑的，肯定的；当然，行

You are certainly a profiteer.
你真是个奸商。

That ring is certainly the cheese.
那只戒指无疑是精品。

You are certainly a talented artist.
你当然是位有天赋的艺术家。