Computational linguistic program - Need some help

[Antoine]

Hello,
I am a student in linguistic from France. So excuse me if my english is perfectible.
I follow a course in computational linguistic and I have to create a program from a list of projects proposed by my teacher.
I chose to create one that open a text, delete a specific target language element (in this case, the articles from dutch, het and de) and submit to the user, line by line, the sentences with the missing article and asks for the answer. At the end, it gives the grade, out of the total number of the sentences.
Here it is : https://github.com/GangleriS/fill_in_the...ree/master
There is the program and the test text file.
I have a problem with it :
I do not know why is there two rounds of questioning as you will see. And when I try to adjust, like :
while i<=2 and o<=2:
or
while i<len(questions) and o<len(words):
that give this :
IndexError: list index out of range

Thanks for your help.