1. Come hell o2r high water

makes clear that some future event will happen and no other event will stop it from happening. In spite of all obstacles, no matter what happens, whatever may come.
无论如何；不管什么事情发生。

come hell o2r high water就算天崩地裂…

这个短语的使用时机是当你要去执行一项任务或是做一件事之际，只许成功不许失败的决心。就犹如中文的“就算天崩地裂…”，比喻不论发生什么状况都要去完成使命。可以用在句首当作一句话的开头，或是放在句尾补述。

请看例句：

1） He is determined to finish the job come hell o2r high water.
他决心无论如何都要把工作完成。

2） I don't care what you think! We are going to finish this project come hell o2r high water.
我不管你怎么想。我们是铁了心要完成这项计划的。

3） Ivy: Will you be at the class reunion next year?
Ivy：明年班级聚会，你们会来吗？
Fiona: Yes, we'll be there, come hell o2r high water!
Fiona：会，我们会来。不管任何情况发生！

2. Like water off a duck's back

鸭子身上的毛就像雨衣一样，水在上面呆不住，一下全滑掉了。因此，water off a duck's back (esp of criticisms, etc) without any effect (on sb)就是（尤指批评等）（对某人）不起作用。

请看例句：

1） I keep telling my friend it's foolish to invest all of her money, but it's like water off of a duck's back.
我一直告诉我的朋友，不要那么傻把所有的工资都用在投资上。可是，我的话对他全然不起作用。

2） The docto2rs tell us it's dangerous to smoke, but such good advice rolls off of some people like water off of a duck's back.
医生都告诉我们抽烟对身体是有害的。可是，这种劝告对于有些人来说就像耳边风一样，毫无作用。

3） Their hints about his behaviour were (like) water off a duck's back.
他们示意他举止不当，如同对牛弹琴。