Modern society cannot well do without the contribution that women can make in the professions and other kinds of work. There is a serious shortage of nurses and teachers, to mention only two of the occupations followed by women. It is a waste to give years of training at public expense only to have the qualified teacher or nurse marry after a year or two and be lost forever to her profession. The training, it is true, will help her in her duties as a mother, but if she continued to work, her service would be more widely useful. Many factories and shops, too, are largely staffed by women, many of them married. While here the question of training is not so important, industry and trade would be seriously short of staff if married women did not work. We can see then that there are good reasons for regarding it as desirable that married women should have some occupation outside the home. However, there are serious objections. Schools do not keep children occupied the whole day and school holidays are long. The mother's working day will almost certainly end well after the school day and her holiday will not begin at the same time as her children's. There will be therefore a period when children are not taken care of unless a substitute for the mother can be found, or unless it becomes more generally possible for women to work part-time. There seem to be some grounds for believing that there is more bad behavior among the children of working mothers than among those of mothers who stay at home, but more evidence is required before we can be certain of this. What we can be certain of, however, is that many more will continue to do so. The clause "unless a substitute for the mother can be found" means  _  .
if someone takes over the mother's occupation if no mother works all day if no one takes care of the children for the mother if someone takes care of the children for the mother