It wasn't until they had been informed that household appliances could not be used that they realized that it was very difficult to do household chores without labor-saving equipment.
It wasn't until they had been informed that household appliances could not be used that they realized that it was very difficult to do household chores without labor-saving equipment.
【答案】It wasn't until they had been informed that household appliances could not be used that they realized that it was very difficult to do household chores without labor-saving equipment.