For adult deer, crossing the river is easy as pie.

对于成年白唇鹿来说，渡河不是什么难事。

Will they find it to be easy as pie?

他们会觉得这很容易吗？

Many pies are also good to eat. If something is easy to do, you could say it is easy as pie. But if you do something wrong or bad, you might have to apologize and show you are sorry.

各种派也非常好吃，如果某事很容易办成，你可以说易如反掌(easy as pie)。但如果你做了错事或坏事，你必须得道歉。