every boy and girl是单数还是复数

　　Every boy and girl in Britain has read it.

　　英国的每个男孩和女孩都读过它。

　　Every boy and girl knows that.

　　每个男孩和女孩都知道那件事。

　　And so, there ought to be one fairy for every boy and girl.

　　所以，世界上有一个孩子，就应该有一个小仙女。