“many a +单数名词”应用单数动词

有一读者问： 书上有一例是这样的：

(1)Many a boy and many a girl has been there.

可是有人说这里的has错了，应用have，孰是孰非？

应用has。这个句子相当于：

(2)Many a boy has been there and many a girl has been there.