How many houses are built in our a year . в прощедщем и в будущем времени.
How many houses were built in our city last year? How many houses will be built in our city next year?
How many houses were built in our a year? How many houses will be built in our a nex year? Тут все легко:глаголы не меняешь.Только are меняешь (если в прошедшем на were, если в будущем на will be)