The phrase "be necessary" is commonly used to convey the idea that something is required or essential. However, in order to avoid repetitive language, it may be useful to explore alternative synonyms such as "be vital", "be obligatory", "be imperative", "be essential", "be indispensable", "be crucial", "be significant", or "be important". By using different synonyms for "be necessary", you can add variety and depth to your writing or speech, as well as emphasize the significance of the matter at hand. It is important to choose the right synonym that accurately reflects the weight of the situation and adheres to the intended tone of communication.