Answer:
Oxymorons and opposition.
Step-by-step explanation:
Shakespeare made use of figures of speech such as oxymorons and opposition to give the idea of contrast in relation to themes, characters, and structure.
OXYMORON is the figure of speech by which two contradictory ideas are put together, for example, "mortal immortal".
In Romeo and Juliet, some oxymorons are "star-cross'd lovers", and "death-mark'd love", stated at the very beginning of the play, but there are many others in all the story.
As regards OPPOSITION, the author plays with the idea of life/death, and light /dark. Moreover, Shakespeare presents two opposing families (the Montague's and the Capulet's) holding an ancient conflict.