"When do you open tomorrow?" should be correct. Reported 11/30/2017
I said "At what time do you open tomorrow?" It wasn't accepted because of "at"
I think this should be marked correct as well. Make sure to report it to improve the system!
We already saw 开 in:
开 (kāi) = to open/to start/to turn on
始 (shǐ) = to begin/to start
开始 (kāishǐ) = to start
i wrote "at what time do your doors open tomorrow?" is that not correct?
你们明天几点开门（what time do you open tomorrow
"what time are you open tomorrow" should also work