Fail to let me input "]" ...

Answer 1

Well, it took me 2-3 posts to realize you're talking about the course and then I had to find the questions. They work for me so if this isn't a hardware problem (like a stuck Ctrl key) it may be an app bug on your device - probably write the developer.

Answer 2

works for me

>>> a=["]"]
>>> a
[']']

maybe provide more detail...

Answer 3

What error did it wrote?
Did you have correct type of value ? (str)