Where an oceanic plate collides with a continental plate, the oceanic plate tips down and slides beneath the continental plate forming a deep ocean trench (long, narrow, deep basin.)
(an oceanic plate; collides; with a continental plate) (the oceanic plate tips down and slides beneath the continental plate; forming; a deep ocean trench)
an oceanic plate the oceanic plate tips down and slides beneath the continental plate
collides forming
with a continental plate
a deep ocean trench