and when they had fulfilled the days, as they were returning, the boy Jesus tarried behind in Jerusalem; and his parents knew it not;

When those days were over and they were returning home, the boy Jesus remained behind in Jerusalem, but His parents were unaware He had stayed.

and having finished the days, in their returning the child Jesus remained behind in Jerusalem, and Joseph and his mother did not know,

and had completed the days, as they returned, the boy Jesus remained behind in Jerusalem, and his parents knew not [of it];