答案：单数
many a的意思是“许多”,more than one的意思是“不止一个”,从意义上,它们表示复数,但用作主语时,谓语却习惯上用单数.如：
1、many a
Many a fine man has died in that battle.许多优秀的士兵死于那次战役.
Many a ship has been wrecked on those rocks.许多船只毁于那些礁石之上.
Many a young man has tried and failed.很多年轻人都试过,而且失败了.
Many a successful store has paid its rent cheerfully.许多成功的店铺都非常乐意地付了房租.
2、more than one
More than one man has been dismissed.不止一人被解雇了.
More than one person is involved in this.与此事有牵连的人不止一个.
If things don’t get better,more than one person is going to have to find a new job.
如果情况没有好转,需要另谋新工作的就不是个别人了.
比较：
Many a boy likes swimming.=Many boys like swimming.许多男孩子喜欢游泳.
More than one student has read the book.=More students than one have read the book.不止一个学生读过这书.