That's a piece of cake 

 

That's as easy as pie! 

 

I can do it with my eyes closed

 

请你客气点 

 

Who do you think you're talking to? 

 

Don't get fresh with me (get fresh with 大多用于母亲对孩子的斥责之时) 

 

等着瞧 

 

you'll see 

 

Time will tell 

 

多管闲事 

 

(It is) None of your business 

 

Mind your won business 

 

Who asked you? 

 

This has nothing to do with you