the boy and girl each___a dictionary

Have 楼上的不要误人子弟。
They each have a dictonary.
Each of them has a dictionary.

The boy and girl each have a dictionary.那个男孩和女孩都有一本词典。

注意：这里的each做“The boy and girl”的同谓语，也就是说，主语是“The boy and girl”，复数。

类似的还有：They each have a bike.他们每个人都有自行车。

have
each作the boy and girl的同位语，中心词是the boy and girl,因而是复数

has

has