I remember taking an English course at university in which use of the passive was banned. That was a bit annoying, but okay whatever I would just write more actively. The real crazy part was that the verb "to be" was banned. Sure it's used to build the passive, but "he is a doctor" is _not_ passive. I could never convince the instructor that this made no sense and was required to do say things like "he became a doctor" or whatever trying to find verbs as close to "to be" as possible in meaning. It was pretty idiotic.