Replied "Ad forum itis" and was marked incorrect even though that should be accepted as the english "You" is ambiguous as to number. Be sure to report if it doesn't accept "itis" as well as "is."
Agree. Either remove the 2nd plural "itis," or indicate that the word "you" is supposed to be singular. Imo having it accept both answers ("is" & "itis") increases ambiguity, which isn't ideal for an education application.