To be on the safe side, I added "of the week" after "What day." Didn't work.
Neither did "What date." =(
Just curious - why is "When is your birthday?" wrong? Because it doesn't specify a date in the answer?
In English, we are more likely to "On what day of the week is your birthday?" than to say "What day of the week is your birthday?"
Thank you for saying this, these are extremely confusing for my ESL self and I was wondering why the heck "on" would be wrong
You should be reporting these sentences if they are not accepted.
Thought it would be okay to say "On what day is your birthday?", but it wasn't so.