The phrase "are incumbent upon" refers to a responsibility or duty to complete a certain task or take certain actions. There are numerous synonyms for this phrase that can add variety and precision to one's language. Some examples include "are essential," "are necessary," "are mandatory," "are required," "are obligated," "are compulsory," and "are imperative." Using synonyms can enhance the impact and clarity of one's communication, especially in formal writing or professional settings. By choosing the appropriate synonym for "are incumbent upon," writers can convey their intended meaning effectively and efficiently.