Being urgent is extremely important when it comes to completing tasks on time. It is often used in professional and personal settings where time is of the essence and tasks need to be completed quickly. Some synonyms for the phrase "be urgent" include pressing, crucial, critical, time-sensitive, and essential. These words all convey a sense of urgency and importance, highlighting the need for immediate attention and action. Other words that can be used include imperative, vital, momentous, significant, and expedient. Using these words in place of "be urgent" can help add clarity and emphasis to the importance of completing a task promptly.