There's no keyword. That would be a nice magic solution, but it doesn't exist, at least in part because there is no guaranteed ordering (okay, you could have the keyword only if there is an ORDER BY...). I can write you a query, but that'll take time, so for now I'll give you a few steps and I'll come back and see if you still need help in a bit.
Figure out an ORDER BY, otherwise no order is guaranteed. If there is a time entered field, that's a good choice, or an index, that works too.
Learn to use Row_Number.
Compare the table (with Row_Number) to itself where instance1.row - 1 = instance2.row.