-- This is Great!
-- This is one of the best answers you want to get and to hear to keep your job security;
-- You did you have to do, feel free go to your vacation;
-- Even it take her 100 years to master the skill, it is not your business.
-- Tell her: I knew it is very hard to learn, take it easy, enjoy!
-- Tell your manager: Boss, I did what you told me to do, I tried my best. Here is my MSN ID, ping me when you have trouble during my vacation time.
Thanks!