首先改被动就是主语谓语改变
时态是不用变的
1.Jack washes the bowls every day.
改为The bowls are washed by Jack everyday.
2.I play the ball in the morning.
改为The boll was played by myself(这里最好用myself,外国人很少用me表达自己做的事）in the morning.
还有how many desks do they sell every month?
改为How many desks are sold by them every month?