"all" is not required for the plural "you". It should not mark me wrong for not having "all"
You are right but did you report it? Reported: 2017-11-30
It is still a problem. Reported 11 July 2018
Still there in January 2020. Its almost like they're not reading these comments!
This forum is mainly for our comments and help to each other. To be sure that a course developer will (eventually) see the problem, you have to use the report flag when you check your answer.
"You have not all drunk the tea" is grammatically more correct than "you all". Means the same
That would mean that some of you have drunk the tea, Here, I think the meaning is "none of you have drunk the tea".