How to make 1 rows from 2 rows which are entry and exit dates

Let's say I have a table like this:

I want to end up with 3 rows like these:

I guess I can do it with a Lag function. But what is the correct way of doing this? Thanks in advance.

Supposing that each entrance date has an exit date, you may try the following:

Select D.Person,MAX(Entrance) Entrance, MAX(Exit) Exit
From
(
  Select table_name.*,
         MOD(ROW_NUMBER() Over (Partition By Person Order By Entrance, Exit), 
         COUNT(*) Over (Partition By Person)/2) grp
  From table_name
) D
Group By D.Person, D.grp

See a demo.