The phrase "are constant" refers to something that remains the same or consistent. There are various synonyms that can be used instead of this phrase depending on the context of the sentence. Some synonyms to consider are unchanging, steady, stable, unfaltering, persistent, resolute, unwavering, reliable, dependable, certain, and fixed. Using synonyms can help writers express themselves more precisely and create variation in their writing. For example, instead of saying "the temperatures are constant," one could say "the temperatures remain steady" or "the temperatures are unwavering." Overall, incorporating synonyms can make writing more engaging and impactful.