Verb > Alternate
to place or do (different things) so that one follows the other in a repeated series
(+ object)
To make the appetizer, you should alternate layers of tomatoes and cheese. (=you should place a layer of tomatoes, then a layer of cheese, then a layer of tomatoes, etc.)
The poem/poet alternates fear and hope.
— often + with
The necklace is made by alternating glass beads with shells.
The poem/poet alternates fear and hope with each other. = The poem/poet alternates fear with hope.
(no object)
The light and dark woods alternate to form an elegant pattern around the window.
— often + with
Light woods alternate with dark woods.
— often + between
The poem alternates between fear and hope.
He alternates between riding his bike and taking the bus to work.